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Is There a Gear Lube Specific to GL-4?
My vehicle is a 1992 Nissan 300zx and requires a single GL4 gear oil in the manual 5-speed synchromesh tranny. Does Mobil make a synthetic gear lube that is a specific GL4? I read on the label of some of the products that the gear oil is applicable for GL3,4 and 5 but have been told that it only applies for differentials and not manual trannies requiring a specific GL5. Is that correct?
-- Peter Sushinsky, Orlando, FL
API GL-5 gear oils can be acceptable for differentials but generally are not recommended for transmissions because a GL-5 gear oil has twice as much Extreme Pressure additive for GL-5 quality gear protection. Even though this EP additive is good for gears it can be aggressive and cause corrosion on the soft yellow metals (brass, copper, bronze) found in the bushings, etc., in manual transmissions.