Reply To: Trans. and axle oil viscosity

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Tom, thanks for the kind words. I want to reinforce what Dave has said a couple of times now about using GL-1 (non-hypoid, straight mineral oil) in a Borg-Warner overdrive, which for P-A owners will be only the 1936-38 cars. I now have two Willys-Overland Jeepsters (’48-’49) but the one I’ve had for 28 yrs will soon go elsewhere. The Willys Owners Manual AND Shop Manual are very explicit and emphatic about using GL-1 (straight mineral oil) in the trans & overdrive (lube can migrate between the two) BUT say to use hypoid (extreme pressure–EP) lube (= today’s GL-4) in the differential.

The B-W overdrives were also used in Packard, FoMoCo, Studebaker, and almost all other OD-equipped vehicles (I’m excluding Columbia 2-speed axles, as I know nothing about them), so the GL-1 is THE lube to use in any B-W OD and its transmission.

VBR, George