Issue link: http://read.dmtmag.com/i/859318
Gear Lubricants Background & Properties castrol.com/GPS 800 255 4417 May 2025 GPS Industry Specifications 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. e 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. is 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 aer testing in CEC L-45-T-99, Method C (20 hours). 5 e precision of ASTM Method D 2983 has not been established for determinations made at temperatures below -40°C. is fact should be taken into consideration in any producer-consumer relationship. E4 ' - . . I 1 1 1 I ecastrof