Gear Lubricants
1 800 255 4417
www.castrol.com/GPS
Background & Properties
Industry Specifications
July 2017
Formulation of quality gear lubricants takes a delicate balance of additive chemistry. One of the best ways to
determine lubricant quality is to review service specifications and mechanical test requirements with a fluid's results.
Finding gear oils that meet, or more importantly exceed, the API test standards is the first step to choosing a quality
gear oil.
The most widely used gear lubricants in North America are of API GL-4 (for manual transmission) and API GL-5 for
axles. Since many equipment builders' specifications exceeded that of the above classifications, a new gear oil
classification, API MT-1, was introduced. API MT-1 contains upgraded performance requirements for oils used in
heavy-duty truck and bus nonsynchronized manual transmissions. This specification does not address oils for
synchronized manual transmissions in passenger cars and heavy-duty vehicles.
Physical Requirements for Gear Lubricants Intended for
Axle and Manual Transmission Applications
SAE Viscosity
Grade
Max Temperature for Viscosity of
150,000 cP (°C)
1,2
Kinematics Viscosity at 100°C (cSt)
3
min
4
max
70W -55
5
4.1 --
75W -40 4.1 --
80W -26 7.0 --
85W -12 11.0 --
80 -- 7.0 <11.0
85 -- 11.0 <13.5
90 -- 13.5 <18.5
110 -- 18.5 <24.00
140 -- 24.0 <32.5
190 -- 32.5 <41.0
250 -- 41.0 --
1
Using ASTM D2983
2
Additional low temperature viscosity requirements may be appropriate for fluids intended for use in light-duty synchronized manual transmissions.
3
Using ASTM D 455
4
Limit must also be met after testing in CEC L-45-T-99, Method C (20 hours).
5
The precision of ASTM Method D 2983 has not been established for determinations made at temperatures below -40°C. This fact should be taken
into consideration in any producer-consumer relationship.
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