MIL-PRF-23699 Lubricating Oil, Aircraft Turbine Engine, Synthetic Base, Nato Code Numbers: O-152, O-154, O-156, And O-167This specification covers four classes of gas turbine engine lubricating oils, primarily used for aircraft engines, which have a nominal viscosity of 5 centistokes at 100 ┬░C and which are typically made with neopentyl polyol ester base stocks. This oil is identified by NATO Code Numbers O-152, O-154, O-156, and O-167.

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MIL-PRF-23699G

containing a polymer capable of being broken down by turbulence at high rates of shear;

typical viscosities are 10.7 mm2/s (cSt) at 100 �C and 57 mm2/s (cSt) at 40 �C. ASTM Reference

Fluid A may be obtained from vendors listed in the ASTM D2603 method.

4.4.11 Trace metal content. The trace metal content of the oil for qualification testing shall

be determined both with a Rotating Disc Electrode - Atomic Emission Spectrometer (RDE-AES)

and Inductively Coupled Plasma - Atomic Emission Spectrometer (ICP-AES) spectrometer.

4.4.11.1 Spectrometer standardization. The spectrometer shall be standardized and

correlated in accordance with the JOAP Program Manual, NAVAIR 17-15-50.2 using

MIL-DTL-85694 standards. Immediately after standardizing the spectrometer, five

determinations of the oil for trace metal content shall be performed. The average of the

five determinations shall be reported. Samples requiring trace metal content determinations

may be sent to: Naval Air Station, Hazmart Building 2385, Sample (AIR 4.4.6) � NOAP, 22680

Hammond Road, Patuxent River, MD 20670.

4.4.11.2 ICP adjustments. In accordance with ASTM D5185, modifications that allow for

the adjustments in the dilution of the sample are allowed to accurately measure 2 ppm (mg/kg) of

metals in the ICP-AES spectrometer.

4.4.11.3 Trace metal conformance testing option. Trace metal content for conformance

testing (table III) can be tested using either RDE-AES spectrometer or ICP-AES spectrometer for

the same elements outlined in table I.

4.4.12 Corrosion and oxidation stability. The corrosion and oxidation stability test shall be

performed in accordance with ASTM D4636, Alternate Procedure 2, with the following

modifications:

a. Duplicate tests shall be run at three separate tests temperatures, each conducted for a

72 hour-duration, at the bath or block temperatures of: 175 �2.5 �C, 204 �2.5 �C, and

218 �2.5 �C. The individual results shall be reported.

b. A suitable liquid medium or fluidized sand bath heating apparatus may be used in lieu

of an aluminum block heater.

c. After the sample tube has been in a liquid heating medium (or aluminum block) for 15

minutes, connect the dry air supply, adjust the air flow rate, and begin the test time.

d. An electrolytic grade silver test square shall be substituted for the cadmium plated

steel square; in the 218 �C test, substitute titanium conforming to SAE AMS4900 (or

equivalent), for copper and magnesium; stainless steel or nickel-chrome wire may be

used to tie the metal coupons together at all test conditions.

e. Post test oil viscosity sample is compared with viscosity of new oil samples tested at

40 �C . Post test oil total acid number is compared to the total acid number of the

new oil sample. The total acid number shall be determined in accordance with

SAE ARP5088.

f. The glassware from FED-STD-791, method 5308 can be used.