This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles

for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

Designation: D4636 − 17

Standard Test Method for

Corrosiveness and Oxidation Stability of Hydraulic Oils,
Aircraft Turbine Engine Lubricants, and Other Highly
Refined Oils1
This standard is issued under the fixed designation D4636; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.

INTRODUCTION

This test method is the result of combining Federal Test Methods 5307.2 and 5308.7. Features and
details of both of these test methods are included, but the new test method is basically Method 5307.2
expanded to include Method 5308.7.2

1. Scope* priate safety and health practices and determine the applica-
1.1 This test method covers the testing of hydraulic oils, bility of regulatory limitations prior to use.
aircraft turbine engine lubricants, and other highly refined oils 1.5 This international standard was developed in accor-
to determine their resistance to oxidation and corrosion degra- dance with internationally recognized principles on standard-
dation and their tendency to corrode various metals. Petroleum ization established in the Decision on Principles for the
and synthetic fluids may be evaluated using moist or dry air Development of International Standards, Guides and Recom-
with or without metal test specimens. mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.2 This test method consists of a standard test procedure,
an alternative Procedure 1, and an alternative Procedure 2. As 2. Referenced Documents
there are variations possible with this test method, it will be up 2.1 ASTM Standards:3
to the particular specification to establish the conditions D91 Test Method for Precipitation Number of Lubricating
required. In addition to temperature, the variables to specify if Oils
other than those of the standard procedure or alternative D445 Test Method for Kinematic Viscosity of Transparent
Procedure 1 or 2 are: test time, air flow and humidity, sample and Opaque Liquids (and Calculation of Dynamic Viscos-
frequency, test fluid quantity, and metal specimen(s). ity)
1.3 The values stated in SI units are to be regarded as D664 Test Method for Acid Number of Petroleum Products
standard. No other units of measurement are included in this by Potentiometric Titration
standard. D1193 Specification for Reagent Water
1.3.1 Exception—The values in parentheses in some of the D3339 Test Method for Acid Number of Petroleum Products
figures are provided for information only for those using old by Semi-Micro Color Indicator Titration
equipment based on non-SI units. 2.2 U.S. Federal Test Method Standards:4
1.4 This standard does not purport to address all of the FED-STD-791 Testing Method of Lubricants, Liquid Fuels,
safety concerns, if any, associated with its use. It is the and Related Products
responsibility of the user of this standard to establish appro- Method 5307.2 Corrosiveness and Oxidation Stability of
Aircraft Turbine Engine Lubricants (Withdrawn)
Method 5308.7 Corrosiveness and Oxidation Stability of
Light Oils (Metal Squares)
1
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
3
Subcommittee D02.09.0D on Oxidation of Lubricants. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved June 1, 2017. Published June 2017. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1986. Last previous edition approved in 2014 as D4636 – 14. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D4636-17. the ASTM website.
2 4
FED-STD-791D is the parent document containing both test methods. As of Available from the Standardization Document Order Desk, 700 Robbins,
publication on Nov. 6, 2009, it no longer contains withdrawn Method 5307.2. Avenue, Building 4D, Philadelphia PA 19111-5094 (http://assist.daps.dla.mil).

*A Summary of Changes section appears at the end of this standard

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States

1
 D4636 − 17
MIL-S-13282 Refined Silver (99.95) (P07015) 4. Significance and Use
2.3 Other Standards:5 4.1 This test method simulates the environment encountered
AMS 4616 Silicon Iron Bronze (C65900) by fully formulated lubricating fluids in actual service and uses
AMS 4908 Titanium Alloy—(8 % Mn) Annealed (R56080) an accelerated oxidation rate to permit measurable results to be
AMS 6490 Steel (M50) (T11350) obtained in a reasonable time. The use of metals provides
QQ-A-671 Cadmium Anod (L01900) catalytic reactive surfaces of those materials commonly found
QQ-C-576 Copper Electrolytic Tough Pitch (ETP) (C11000) in real systems. The high temperature and air agitation help
QQ-M-44 Magnesium Alloy AZ31B Condition H24 or H26 accelerate the oxidation reactions that are expected to occur.
(M11311) Moisture in the air adds another realistic condition that
QQ-S-698 Low-Carbon Steel 1010, CR Temper No. 4 or 5 encourages oil breakdown by facilitating acid formation.
(G10100)
QQ-A-250/4 Aluminum Alloy 2024 T-3 or T-4 (A92024) 4.2 Interpretation of results should be done by comparison
with data from oils of known field performance. The acceler-
3. Summary of Test Method ated conditions likely will cause one or more of the following
measurable effects: mass change and corroded appearance of
3.1 This test method consists of a standard test procedure
some metals; change of viscosity; increase in acid number;
(see 10.1), an alternative Procedure 1 (see 10.2), and an
measurable reaction products in the form of sludge; and mass
alternative Procedure 2 (see 10.3). The standard test procedure
loss of oil due to evaporation.
uses washer-shaped metal specimens stacked on the air tube,
200 mL of test oil, 10 L ⁄h air flow rate, and periodic test oil 4.3 This test method is most suitable for oils containing
withdrawal and evaluation. Alternative Procedure 1 uses oxidation and corrosion inhibitors. Without such ingredient(s),
washer-shaped metal specimens, 165 mL of test oil, 10 L ⁄h air the severe test conditions will yield rather drastic changes to
flow rate, and no periodic test oil sampling. Alternative the oil.
Procedure 2 uses square metal specimens tied together resting
vertically in the large glass tube, 100 mL of test oil, 5 L ⁄h air 5. Apparatus
flow rate, and no periodic test oil sampling. 5.1 The main apparatus consists of the following items of
NOTE 1—Flow rates other than those listed in this test method may be standard wall borosilicate glassware as shown in Figs. 1-5:
required by various specifications; if they are so used, the modification to 5.1.1 Main Sample Tube (Fig. 1).
the test method should be stated in the test report.
5.1.2 Sample Tube Head (Fig. 2).
3.2 A large glass tube containing a sample of oil and metal 5.1.3 Air Tube (Note 2, Fig. 3).
specimens is placed in a constant temperature bath and heated
for the specified number of hours while air is passed through NOTE 2—An 800 mm air tube may be used for alternate Procedure 1 or
2 when using the condenser as opposed to the sample tube head in the
the oil to provide agitation and a source of oxygen. Typically, standard procedure.
temperatures of the bath used are from 100 °C to 360 °C.
Weighed metal specimens are placed in the tube during the test. 5.1.4 Condenser, Allihn Type (Fig. 4).
Corrosiveness of the oil is determined by loss in metal mass, 5.1.5 Condenser, Allihn Type, Fig. 4 with 71/60 joint.
and microscopic examination of the sample metal surface(s). 5.1.6 Assembled Apparatus (Fig. 5).
Oil samples are withdrawn from the test oil and checked for 5.2 Additional glassware items and assembly accessories
changes in viscosity and acid number as a result of the needed are:
oxidation reactions. 5.2.1 Spacers (for Metal Specimen), of borosilicate glass,
3.3 Metals used in the basic test and alternative Procedure 1 standard wall, 9 mm outside diameter, 6 mm length.
are titanium, magnesium, steel (two types), bronze, silver, and 5.2.2 Oil Sampling Tube, Borosilicate Glass, 4 mm outside
aluminum. Metals used in alternative Procedure 2 are copper, diameter, with sampling end approximately 600 mm to reach
steel, aluminum, magnesium, and cadmium. Other metals may into the main sample tube. The tube is bent U-shape with exit
be specified. end fitted by a one-hole stopper to a 25 mL filtering flask. The
3.4 Sampling of the oil for analysis is done periodically exit end may be any convenient length.
throughout the test. Alternatively, no periodic samples are 5.2.3 Adapter, polytetrafluoroethylene for 10/18 joint for
taken and a final viscosity and acid number are determined for sealing of air tube to sample tube head.
comparison with those of the original untested oil. 5.3 Other items and equipment are:
3.5 At the end of the test, the amount of sludge present in 5.3.1 Heating Bath, constant temperature within 60.5 °C of
the oil remaining in the same tube is determined by centrifu- test temperature with an immersion depth of 250 mm 6
gation. Also, the quantity of oil lost during the test is 20 mm. Oil baths or aluminum block baths are recommended,
determined gravimetrically. but above 220 °C, use aluminum block bath or other similar
3.6 Air is used dry in the standard test. A humidifier may be non-oil-type heating medium. (Warning—There are exposed
used to provide controlled moist air, if required. hot surfaces on apparatus. Avoid contact with exposed skin by
use of protective equipment as required.)
5.3.2 Hood, ventilation to adequately remove fumes during
5
See ASTM DS 56, Metal and Alloys in the Unified Numbering System. heating.

2
 D4636 − 17
anhydrous calcium sulfate with a column diameter such that
velocity of air does not exceed 1.2 m/min. For humidifying, a
satisfactory device is included in Appendix X1 to provide the
required moist air.
5.3.13 Oven, optional, to dry glassware at elevated tempera-
ture.
5.3.14 Forceps, stainless steel.
5.3.15 Thermocouple, 70 cm sheathed. (See Note 3.)
NOTE 3—A resistance temperature device (RTD) is also acceptable.
5.3.16 Brush, short-bristled, stiff (typewriter-cleaning brush
or equivalent).

6. Reagents and Materials

6.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
all reagents conform to the specifications of the Committee on
Analytical Reagents of the American Chemical Society where
such specifications are available.6 Other grades may be used
provided it is first ascertained that the reagent is of sufficiently
high purity to permit its use without lessening the accuracy of
the determination.
6.2 Purity of Water—Unless otherwise indicated, references
to water shall be understood to mean reagent water as defined
by Specification D1193. Referee situations require Type II
distilled water defined by Specification D1193.
6.3 Metal Specimens:7, 8
6.3.1 Washer-Shaped Metal Specimens, 6.35 mm inside di-
ameter by 19.05 mm (3⁄4 in.) outside diameter by 0.81 mm
thick in the following metals:
R56080 Titanium 8 % Mn
M11311 Magnesium AZ31B
T11350 Steel M50
G10100 Steel grade 1010
FIG. 1 Sample Tube C65900 Silicon-iron-bronze
P07015 Silver 99.95
A92024 Aluminum Alloy 2024 T-3 or T-4

5.3.3 Air Supply, free of reactive contaminants. For dry air, 6.3.2 Square-Shaped Metal Specimens (as shown in Fig. 6),
dew point is −68 °C maximum; for moist air, moisture is 10 mg 0.81 mm by 25.4 mm square in the following metals:
6 1 mg water ⁄L air, standard conditions of 21 °C ⁄105 kPa. C11000 Copper (ETP)
G10100 Steel Grade 1010
5.3.4 Flowmeter, capable of measuring 10 L ⁄h 6 1 L ⁄h at A92024 Aluminum Alloy 2024 T-3 or T-4
same standard conditions as in 5.3.3. M11311 Magnesium AZ31B
5.3.5 Balance, analytical, sensitivity 0.1 mg. L01900 Cadmium Anod

5.3.6 Balance, Laboratory, 2500 g capacity, 0.1 g sensitiv- 6.4 Abrasive Paper, silicon carbide of 240 and 400-grit.
ity. “Wet or dry,” “waterproof,” or iron-containing abrasives, such
5.3.7 Centrifuge, capable of relative force of 840 6 40 as natural emery, are not satisfactory.
relative centrifugal force at the tip of the tubes. 6.4.1 Silicon-Carbide Grains, 150 mesh.
5.3.8 Centrifuge Tubes, Test Method D91, cone-shaped, 6.5 Cotton, absorbent.
100 mL.
5.3.9 Microscope, with 20-diameter magnification.
5.3.10 Assembly Fixture, wood (slotted to hold metal 6
Reagent Chemicals, American Chemical Society Specifications, American
squares for tying with cord) as shown in Fig. 6. Chemical Society, Washington, DC. For suggestions on the testing of reagents not
5.3.11 Cord or Wire, for tying metal squares together. listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Suitable cord should be lightweight of cleaned linen, cotton, and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
nylon, or ceramic fiber; suitable wire is nichrome or tantalum. MD.
7
5.3.12 When air must be conditioned, there is need for an air The sole source of supply of the metal specimens known to the committee at
this time is Metaspec Co., P.O. Box 27702, San Antonio, TX 78227-0707.
drier or humidifier. The method used is optional provided the 8
If you are aware of alternative suppliers, please provide this information to
air characteristics of 5.3.3 are attained. For drying, a satisfac- ASTM International Headquarters. Your comments will receive careful consider-
tory method is the use of a glass column containing 8-mesh ation at a meeting of the responsible technical committee 1, which you may attend.

3
 D4636 − 17

FIG. 2 Sample Tube Head

6.6 n-Heptane. (Warning—Flammable. Harmful if in- 6.11 Glassware Cleaning Solution (Warning—Causes se-
haled.) vere burns.)—Mix 35 mL of MICRO10 in water or 35 mL of
6.7 Acetone. (Warning—Extremely flammable. Vapors NOCHROMIX11 and 1000 mL of concentrated sulfuric acid.
may cause flash-fire.) 6.12 Metal Cleaning Solution—Mix equal parts of 15 g
6.8 Nitric Acid, concentrated. (Warning—Poison. Corro- NaOH per litre of water and 15 g of Na3PO4 per litre of water.
sive. Strong oxidizer.) (Warning—Corrosive.)
6.9 Degreasing Solvents, n-Heptane or toluene. See Note 4. 7. Hazards
NOTE 4—n-Heptane or toluene have been used in some laboratories; 7.1 As this test method investigates the corrosive effect of
however, it is not known how this may affect the precision statement,
which was determined using chlorinated solvents.
oil on metal in an artificial environment, precautions must be
taken to prevent premature oxidation of metal specimens by
6.10 Carbon Remover for Glassware9, 8(Warning—Causes stray chemicals during test preparations. The cleaned speci-
severe burns.)—Mix 35 mL of saturated sodium dichromate mens shall be touched only by surfaces known to be free of
(aqueous) solution and 1000 mL of concentrated sulfuric acid. interfering contaminants. Do not touch cleaned specimen(s)
(Warning—Corrosive.) with hands. Maintain clean glassware (see Appendix X2) in a

9
The sole source of supply of the carbon remover for glassware known to the
10
committee at this time is Oakite Products, Inc., 50 Valley Rd., Berkeley Heights, NJ International Products Corp., P.O. Box 70, Burlington, NJ 08016-0070.
11
07922. Godax Laboratories, Inc., 720-B Erie Avenue, Takoma Park, MD, 20912.

4
 D4636 − 17

FIG. 4 Condenser, Allihn Type

FIG. 3 Air Tube NOTE 5—Square metal specimens are required by alternative Procedure
2 in 10.3.
8.2.4.1 Finish polishing with 400-grit paper to remove
dust-free cabinet; rinse again and dry if clean glass has been
marks from previous polishing. A good technique is to place
stored unused for more than a week.
abrasive paper on flat surface, then rub the specimen with
7.2 Heating Bath, n-heptane, toluene, acetone, carbon longitudinal strokes in a direction perpendicular to that used
remover, nitric and sulfuric acids, and sodium hydroxide all with 240-grit paper. Use a different sheet of paper for each
require caution in handling as detailed in 5.3.1 and 6.6 – 6.12. metal type.
8.2.4.2 Swab polished specimens with n-heptane followed
8. Sampling by acetone until a fresh cotton pad remains clean when wiped
8.1 As this test method is performed on uniform, finished on the specimen.
oils, no special sampling procedure is needed for this oil. 8.2.4.3 Finish polishing both sides of each specimen to a
8.2 Preparation of Metal Specimens: mirror finish using 150-mesh silicon-carbide grit (held on an
8.2.1 Collect the required number and types of specimens to acetone-moistened cotton pad).
be used in the test method. Measure the diameter of each 8.2.4.4 Clean all metal dust from each square by rubbing
specimen and specimen hole to the nearest 0.1 cm. vigorously with clean pads of absorbent cotton until a fresh pad
8.2.2 Clean and polish the metal specimen face surfaces and remains unsoiled.
inner and outer edges using 240-grit abrasive paper. Examine 8.2.4.5 Wash specimens in n-heptane, rinse with fresh
surfaces to ensure that no pitting, etching, or other signs of solvent, and allow to air dry.
corrosion are present when viewed at 20× under the micro- 8.2.5 Store specimens in a dust-free place if to be used
scope. immediately or under n-heptane if there is to be delay before
8.2.3 From this point, handle specimens only with forceps, use.
ashless filter paper, or clean polyethylene gloves. Store speci- 8.2.6 Immediately prior to use, dry and weigh each metal
men immersed in separate containers of acetone until ready for specimen to the nearest 0.1 mg.
final polishing. 8.3 Oil Sample Size (Note 6 and Note 7):
8.2.4 Finish polishing metal washer specimens or square 8.3.1 The total sample requirement is 250 mL, 200 mL 6
metal specimens. Use either technique described in 8.2.4.1 or 2 mL for test and 50 mL for pretest determination of viscosity
8.2.4.3. and acid number.

5
 D4636 − 17
9. Preparation of Apparatus
9.1 Cleaning of Glassware (from Previous Run):
9.1.1 Rinse all glassware items and the air tube adapter with
degreasing solvent to remove residual oil, and air dry.
9.1.2 Fill or immerse the sample tube, air tube, and the
9 mm glass spacers in carbon remover at room temperature
until carbonaceous deposits are removed. Water rinse after
removal.
9.1.3 Wash all glassware items and the air tube adapter with
detergent.12, 8 Rinse with water to remove detergent, and dry.
9.1.4 Fill and immerse all glassware items with glassware
cleaning solution and soak for 3 h to 16 h (see Note 8).
NOTE 8—This cleaning procedure is only necessary in a referee
situation unless a cleaning solution, which is satisfactory to all parties
involved, can be used.
9.1.5 Remove glassware from cleaning solution, rinse sev-
eral times with tap water followed by distilled water, and oven
dry (see Note 8).
9.1.6 Store all items in a dust-free cabinet until needed for
test. If stored longer than 1 week, rinse again before use with
distilled water and dry.
9.2 Cleaning of Glassware (New)—Proceed as in 9.1.3 and
9.1.6 in that order (omit 9.1.1, 9.1.2, 9.1.4, and 9.1.5).
9.3 Assembly—Assemble as shown in Fig. 5, using only the
test oil to lubricate glass joints during assembly.
FIG. 5 Assembled Apparatus
10. Procedure
10.1 Standard Test Procedure:
10.1.1 Determine acid number of the test oil in accordance
with Test Method D664.
10.1.2 Determine the kinematic viscosity of the test oil at
40 °C and 100 °C in accordance with Test Method D445.
10.1.3 Turn on heating control to bring temperature of
heating medium to a temperature that will maintain the oil
sample within 60.5 °C of the specified temperature
(Warning—There are exposed hot surfaces on apparatus.
Avoid contact with exposed skin by use of protective equip-
ment as required.).
10.1.4 When assembling the clean sample tubes and
accessories, use only the actual test oil to lubricate joints of
each assembly.
10.1.5 Slide the prepared metal washer specimens onto the
air tube in the following order: aluminum (bottom), silver,
bronze, low carbon steel, M50 steel, magnesium, and titanium
(top). Use one glass spacer only between each metal specimen.
10.1.6 Place the air tube with specimens into the sample
FIG. 6 Metal Square Dimensions and Arrangement tube.
10.1.7 Position the sample tube head on the sample tube
with the air tube protruding through the center glass joint.
NOTE 6—An alternative Procedure 1, which deletes the requirement for
10.1.8 Seat the TFE-fluorocarbon adapter on the air tube
periodic oil sampling throughout the test period may be specified. with the air tube resting on the bottom of the sample tube and
Alternative Procedure 1 requires an initial oil charge of 165 mL 6 2 mL tighten the gland.
(see 10.2).
NOTE 7—An alternative Procedure 2, which deletes the requirement for
periodic oil sampling and requires square metal specimens instead of
washer-shaped metal specimens may be specified. Alternative Procedure 2 12
The sole source of supply of the detergent known to the committee at this time
requires an initial oil charge of 100 mL 6 1 mL (see 10.3). is Alconox, Inc., 215 Park Avenue South, New York City, NY 10003.

6
 D4636 − 17
10.1.9 Insert the 70 cm long-sheathed thermocouple making 10.1.23.3 Remove the air tube, polytetrafluoroethylene
sure the closed end of the sheath is at least 10 mm from the adapter, and sample tube head.
sample tube wall. 10.1.23.4 Remove the air tube with metal specimens, rinse
10.1.10 Weigh the entire apparatus to the nearest 0.1 g. with n-heptane or toluene, and slide the specimens off the air
10.1.11 Add 200 mL 6 2 mL of test oil in accordance with tube carefully into a clean absorptive surface. Keep the
8.3 to the sample tube, reweigh entire assembly to the nearest specimens in order for identification, but if processing of
0.1 g, and determine the mass of the sample added. specimens is to be delayed, store them under n-heptane.
10.1.12 Position the sample tube in the heat medium at test 10.1.23.5 Drain the test oil completely from the sample tube
temperature to an immersion depth of 250 mm 6 20 mm. into a clean glass container and hold for sludge determination.
10.1.13 Insert the condenser and start water flow. Maintain Note the appearance of any deposits on the inside of the sample
water temperature at 18 °C 6 3 °C. tube.
10.1.14 Connect the thermocouple. 10.1.24 Sludge Determination—Take a representative
10.1.15 After the sample tube has been in a liquid heating portion, after well stirring the final test oil, and centrifuge a
medium for 15 min, connect the dry air supply, adjust the air 25 mL aliquot for 1 h at a relative centrifugal force of 840 6 40
flow rate to 10 L ⁄h 6 1 L ⁄h, and begin the test time. For an in accordance with Test Method D91. Record the volume of
aluminum block heating medium without liquid heat transfer solid or semisolid sludge obtained to the nearest 0.1 mL.
medium, allow 1 h between insertion of sample tube into heater 10.1.25 Metal Specimens, Post-Test Processing:
and start of air flow and timing. 10.1.25.1 Rinse the metal specimens individually with
10.1.16 Adjust heat control to ensure oil sample tempera- n-heptane or toluene. Wipe each metal specimen with
ture is held within 60.5 °C of required value. Verify sample n-heptane or toluene-wetted cotton pads until a fresh pad
temperature and air flow occasionally during test specifically remains clean.
just prior to each sampling time. 10.1.25.2 Rinse each specimen with clean n-heptane, then
10.1.17 Sample the test oil (10 mL sample) at the following acetone, then air dry and weigh to the nearest 0.1 mg.
times: 16 h, 24 h, 40 h, 48 h, 64 h, 72 h, 88 h, and 96 h. 10.1.25.3 If there are visible carbon deposits remaining on
10.1.18 Preweigh the sample flask, stopper, and tube to the the specimens, clean as indicated in Appendix X2.
nearest 0.1 g so that an accurate mass of sample withdrawn can 10.2 Alternative Procedure 1:
be determined. 10.2.1 Perform the standard test as in 10.1 except as
10.1.19 Perform sampling by withdrawing the thermo- follows:
couple sheath and inserting the 4 mm tube attached to the 10.2.2 Use 165 mL 6 2 mL of the sample at the start.
sampling flask. Using a rubber bulb or similar source of slight 10.2.3 Do no periodic sampling. Sample the oils only at
suction on the flask tube, draw the required sample to a completion of the test time. No sample tube head is needed.
premarked level in the sampling flask. Do not interrupt air flow Use the condenser described in 5.1.5.
nor remove the same tube from the heat during sampling. 10.3 Alternative Procedure 2:
10.1.20 Determine and record mass of each sample re- 10.3.1 Perform the standard test as in 10.1 except as
moved during test. follows:
10.1.21 Determine acid number in accordance with Test 10.3.2 Use 100 mL 6 1 mL of the sample at the start.
Method D664 of all samples. 10.3.3 Use 5 L ⁄h 6 0.5 L ⁄h air flow rate.
NOTE 9—If acid number is not determined on the same day of sampling, 10.3.4 Do no periodic sampling. Sample the oil only at
samples should be refrigerated up to a maximum of 1 week prior to completion of the test time. No sample tube head is needed.
determination. Use the condenser described in 5.1.4 or 5.1.5.
10.1.22 Determine viscosity in accordance with Test 10.3.5 Instead of washer-shaped metal specimens, use
Method D445 at 40 °C on all samples and viscosity at 100 °C square metal specimens as defined in 6.3.2.
on original and final sample only. 10.3.5.1 Arrange metal squares in a wooden assembly
fixture in the pattern shown in Fig. 6, making certain that the
NOTE 10—Due to the reduced sample volume availability, viscosity
measurement is made using the semimicro viscometers listed in Test magnesium and copper squares do not touch each other.
Method D445. In addition, it may be necessary to determine acid number 10.3.5.2 Clean the cord or wire by boiling in distilled water
using a titration sample size less than that required by Test Method D664. for 10 min and allow to air dry.
The semimicro Test Method D3339 may be used to determine acid 10.3.5.3 Using forceps or cotton (linen) gloves, or both, to
number.
handle the cord or wire, tie the squares together as shown in
10.1.23 Shutdown: Fig. 6. Due to potential contamination, use of latex gloves is
10.1.23.1 After the final sample is taken, shut off the air not recommended.
flow and condenser water, remove the condenser, and discon- 10.3.5.4 Insert the tied metal squares into the sample tube,
nect the thermocouple. Note the presence of liquid or solid positioning the squares vertically (so that the air tube can be
material on the inside of the condenser. inserted to touch the bottom of the tube).
10.1.23.2 Remove the sample tube from the heat medium, 10.3.5.5 When the oil specification requires only two metal
wipe tube exterior, allow to cool, and, if necessary, clean the specimen squares, place the squares in the sample tube in such
tube exterior by rinsing with n-heptane or toluene. Weigh the a manner as to form a “V” in the bottom of the tube. No tying
assembly to the nearest 0.1 g. is necessary.

7
 D4636 − 17
10.3.6 Upon completion of 10.1.23.3, prepare square metal 12. Report
specimens for examination as follows: 12.1 Report kinematic viscosity, expressed in centistokes
10.3.6.1 Use forceps to withdraw the metal squares from the (millimetres squared per second) for initial and final samples at
test tube and remove the cords holding them together. 40 °C and 100 °C. Report percentage change to the nearest
10.3.6.2 Using forceps, wash each square individually in 0.1 % from original viscosity for all periodic and final samples
n-heptane or toluene. at 40 °C and for final sample at 100 °C.
10.3.6.3 Repeat the washing, using fresh n-heptane or
toluene and scrubbing the squares with the short-bristled brush 12.2 Report the acid number for original and final samples,
until the solvent shows no additional discoloration, and allow expressed in mg KOH/g. Report the change in neutralization
the squares to dry. Alternatively, scrubbing with n-heptane- number in milligrams KOH/g for all periodic and final
moistened 100 % cotton balls until they look clean has also samples.
been found acceptable. 12.3 Report the mass change of each metal specimen from
10.3.6.4 Weigh each square to the nearest 0.1 mg. Measure the initial. When Appendix X2 cleaning is used, report mass
the face dimensions of each panel to the nearest 0.1 cm. change before and after electrocleaning or nitric acid soak.
Express the change in milligrams per squared centimetres
11. Calculation calculated to the nearest 0.1 mg ⁄cm2.
11.1 Calculate the oil mass loss as follows: 12.4 Report the appearance of the metal specimens after
cleaning with respect to any pitting, etching, or other corrosion
W 2 2 ~ W 3 1W 4 !
% Loss 5 3 100 (1) observed without magnification and with 20× magnification.
W2 2 W1
12.5 Report the volume % of sludge in oil to the nearest
where: 0.1 mL.
W1 = mass of tube assembly,
W2 = mass of tube assembly plus sample at start, 12.6 Report the weight percent of oil loss during test to the
W3 = mass of tube assembly plus sample at end of test, and nearest 0.1 %.
W4 = accumulated mass of samples removed during test. 12.7 Report the test conditions and any irregularities or
11.2 Calculate the viscosity change as follows: deviations from required test procedures and conditions.
12.8 Report the presence of liquid or solid material on the
% Viscosity change 5 S V2 2 V1
V1 D
3 100 (2) inside of the condenser at the end of the test.
12.9 Report the appearance of the deposit on the sample
where:
tube at the end of the test.
V1 = viscosity before test, cSt (mm2/s), and
V2 = viscosity after test, cSt (mm2/s). 13. Precision and Bias
11.3 Calculate the neutralization number change as follows: 13.1 Precision was determined under test conditions of
Acid number change, mg KOH/g 5 T 2 2 T 1 (3) 175 °C for a 96 h duration using the standard test procedure
and alternate Procedure 1. Precision for alternate Procedure 2
where: was not determined. The precision of this test method as
T1 = acid number before test, mg KOH/g, and determined by statistical examination of interlaboratory test
T2 = acid number after test, mg KOH/g. results in the ranges indicated is stated in Tables 1-3.
11.4 Calculate the metal specimen mass change as follows: 13.1.1 Repeatability—The difference between successive
test results obtained by the same operator with the same
Metal mass change, mg/cm 2 5 ~ M 2 2 M 1 ! /A (4)
apparatus under constant operating conditions on identical test
where: material would, in the long run, and in the normal and correct
M1 = mass of specimen before test, mg, operation of the test method, exceed the following value only
M2 = mass of specimen after test, mg, and in one case in twenty.
A = area of metal specimen based on the face surface 13.1.2 Reproducibility—The difference between two single
without consideration for the edge area, cm2. and independent results, obtained by different operators work-
ing in different laboratories on identical test material would, in
11.4.1 For washer specimens:
the long run, and in the normal and correct operation of the test
π method, exceed the following value only in one case in twenty.
A5
2
~ D 22 2 D 21 ! (5)

where: TABLE 1 Precision Table for Percent Change in Viscosity at

40 °C and at 100 °C in the Range 0 % to 12 %
D1 = initial diameter of hole, nearest 0.1 cm, and
D2 = initial diameter of specimen, nearest 0.1 cm. Repeatability, Reproducibility,
% Change % Change
11.4.2 For square specimens: Standard 1.6 3.2
Test Procedure
A 5 2 LW (6) Alternate 2.0 2.7
Procedure 1
where L and W are the two face dimensions, nearest 0.1 cm.

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TABLE 2 Precision Table for Acid Number Change
Repeatability Reproducibility
Range of Change in Standard Test Alternate Standard Test Alternate
Acid Number mg Procedure Procedure 1 Procedure Procedure 1
KOH/g
0.0 to 1.0 0.32 0.23 0.69 0.62
1.0 to 2.0 0.49 0.36 1.53 1.43

TABLE 3 Precision Table for Corrosion Up to 0.3 mg ⁄cm

Repeatability Reproducibility
Standard and Alternate Procedure 1 0.2 0.3

13.2 Bias—Since there is no acceptable reference material 14. Keywords

suitable for determining the bias procedure for measuring 14.1 hydraulic fluid; lubricant; oxidation stability
corrosiveness and oxidation stability of hydraulic oils, aircraft
turbine engine lubricants, and other highly refined oils in Test
Method D4636, bias cannot be determined.

APPENDIXES

(Nonmandatory Information)

X1. TEST GAS HUMIDITY CONTROL

X1.1 Air Humidifier—The precise method of humidifying X1.1. Air enters through a length of 0.95-cm tubing and
the test air is optional. A satisfactory device is shown in Fig. discharges through a 2.54-cm diameter diffuser stone. The

FIG. X1.1 Air Moisturizer

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 D4636 − 17
controlled temperature is that indicated by the thermocouple X1.2.1 The air temperature is monitored daily; however,
near the air exit fitting. One heater is operated by an on-off with satisfactory insulation, the transformer setting should not
switch and used only for initial preheating. A second heater is require adjustment during a 96 h test.
in circuit with a variable voltage transformer. The transformer
is adjusted to control the air exit temperature required to give X1.3 The exit air temperature is selected to obtain the
the proper moisture content. The stainless steel tank 13, 8 is desired moisture content. Moisture content may be determined
insulated over the entire exterior surface and placed within a gravimetrically using a U-shaped Schwartz tube with standard-
refrigerator. The air exit fitting and line are well insulated to taper glass stoppers. The tube is filled with anhydrous calcium
avoid moisture condensation. The exit line length within the sulfate and weighed to the nearest 0.1 mg. The air moisturizer
refrigerator is held to a minimum and the downstream portion is allowed to temperature equilibrate at the required total
of the line between the refrigerator and sample tube must not airflow. While maintaining the total flow through the
encounter a temperature region lower than the control moisturizer, the weighing tube is connected to any one of the
temperature, or condensation will occur. sample tube air lines. After a 1 h flow period, the tube mass
X1.2 The preceding apparatus will satisfactorily serve as an gain should be 100 mg 6 10 mg. If necessary, adjust air exit
air humidifier for several sample tubes, up to a known total of temperature control to obtain proper moisture content. Any
16. At this flow rate (160 L ⁄h), the following control param- change in the total air flow necessitates recalibration of
eters are typical for achieving a moisture of 10 mg of water/L moisture content since the air velocity through the moisturizer
of air: could affect the relative humidity of the air. In the event that a
Exit air temperature 15 °C test is performed with a lesser number of sample tubes than that
Water temperature 15.6 °C for which originally calibrated, unused flowmeters should be
Refrigerator temperature 12.2 °C
Control heater power >10 W
left on to maintain the normal total airflow.

13
The sole source of supply of the stainless steel tank known to the committee
at this time is A. C. Tank Co., POB 389, Burlington, WI 53015.

X2. SPECIMEN CLEANING

X2.1 If there are visible deposits on the specimens, they loose deposits. (Repeat the electrocleaning step, as necessary,
must be electrocleaned. The individual specimens, except to remove all deposits.) Rinse the specimens in acetone, air dry,
aluminum, are cathodically cleaned in hot 75 °C to 85 °C and reweigh. Soak the aluminum specimen in concentrated
electrocleaning solution (see 6.12) for a period of 15 s to 30 s nitric acid for 15 min, then water rinse, and swab with cotton
to a current density of 0.08 amp ⁄cm2. Remove from the to remove loose deposits. (Repeat the cleaning as necessary to
bath,8, 14 rinse in tap water, and swab with cotton to remove remove all deposits.) Rinse the specimens in acetone, air dry,
and reweigh.
14
A satisfactory bath for electrocleaning consists of a 1 L glass beaker, hot plate, NOTE X2.1—If metal types other than those cited in this test method are
and variable dc voltage source capable of supplying current of 1 A. The sole source used, the compatibility of the electrocleaning procedure with metal
of supply of the voltage source known to the committee at this time is Electro composition should be determined and, if necessary, other appropriate
Products Laboratories, Inc., 6125 W. Howard Street, Chicago, IL 60648. procedures used.

SUMMARY OF CHANGES

Subcommittee D02.09.0D has identified the location of selected changes to this standard since the last issue
(D4636 – 14) that may impact the use of this standard. (Approved June 1, 2017.)

(1) Revised Eq 4 in subsection 11.4.

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