Mobil Avrex S Turbo 256  

ExxonMobil Aviation, United States

Aircraft Type Gas Turbine Lubricant

Product Description

Mobil Avrex S Turbo 256 gas turbine lubricant is a combination of a highly stable synthetic base fluid and a unique chemical additive package. The combination provides outstanding thermal and oxidative stability to resist deterioration and deposit formation in both the liquid and vapor phases, as well as excellent resistance to foaming.

The effective operating range of Mobil Avrex S Turbo 256 is between -54°C and 176°C (-65°F and 350°F). The pour point is below -60°C (-75°F). The product has a high specific heat in order to ensure good heat transfer from oil-cooled engine parts. In extensive laboratory testing and in-flight performance, Mobil Avrex S Turbo 256 exhibits excellent bulk oil stability at temperatures up to 176°C (350°F). The evaporation rate at these temperatures is low enough to prevent excessive loss of volume.


Mobil Avrex S Turbo 256 is recommended for aircraft gas turbine engines in commercial and military service, particularly where start-up temperatures are below -40°C (-40°F). The product is approved against U.S. Military Specification MIL-PRF-7808, Grade 3, and by the following engine and accessory manufacturers:

Engine and Accessory Approvals

Approved in equipment specifying 3 centistokes, MIL-PRF-7808 (latest revision) lubricants. Mobil Avrex S Turbo 256 is compatible with other synthetic gas turbine lubricants meeting MIL-PRF-7808 or MIL-PRF-23699 Specifications. However, mixing with other products is not recommended because the blend would result in some loss of the performance characteristics of Mobil Avrex S Turbo 256. The product is compatible with all metals used in gas turbine construction, as well as with F rubber (Viton A), H rubber (Buna N), and FVMQ rubber (fluorosilicone).


Uniquely suited for use when extreme low temperatures restrict the use of higher viscosity engine oils.

Typical Properties

Avrex S Turbo 256 MIL-PRF-7808 Grade 3 Requirements
Product Number 49423-7 -
cSt at 100°C (212°F) 3.3 3.0 min
cSt at 40°C (104°F) 13.3 11.0 min
cSt at -51°C (-60°F) after 3 hr 10,459 17,000 max
cSt at -51°C (-60°F) after 72 hr 10,495 17,000 max
Flash Point, °C (°F) 224 (435) 210 (410) min
Fire Point, °C (°F) 256 (493) -
Pour Point, °C (°F) -60 (-75) -
Specific Gravity, 15/15°C (60/60°F) 0.9634 -
TAN, mg KOH/g 0.03 0.30 max
Evaporation Loss, %
6.5 hr at 204°C (400°F) 19.6 30 max
Foam, volume/collapse time
Static, ml/sec 20/6 100/60 max
Dynamic, ml/sec pass 100/60 max
Rubber Swell, %
H Rubber, 168 hr at 70°C (158°F) 28.6 12-35
F Rubber, 72 hr at 175°C (347°F) 19.1 2-25
FS Rubber, 72 hr at 150°C (302°F) 10.6 2-25

Health and Safety

Based on available information, this product is not expected to produce adverse effects on health when used for the intended application and the recommendations provided in the Material Safety Data Sheet (MSDS) are followed. MSDS's are available upon request through your sales contract office, or via the Internet. This product should not be used for purposes other than its intended use. If disposing of used product, take care to protect the environment.

The ExxonMobil logotype, Mobil and Avrex S Turbo are trademarks of Exxon Mobil Corporation, or one of its subsidiaries. PDSAV-13


Exxon Mobil Corporation
22777 Springwoods Village Parkway
Spring TX 77389

For additional technical information or to identify the nearest U.S. ExxonMobil supply source, call 1800 662-4525.

Due to continual product research and development, the information contained herein is subject to change without notification.  Typical Properties may vary slightly.