Can regular 85w-90 hypoid gear lubricant be used in a 1993 ford ranger manual transmission gearbox in which the manual calls for automatic transmission fluid?

Answer 1

Absoultly not!!!!! This particular transmission is designed to use A/T fluid. Why would you even consider this? Just installed new shaft seals at the input and output shafts. Transmission has a different sound now when in neutral at idle. Goes away when the clutch is depressed and the input shaft stops turning. Sound doesn't bother me but my son complains about it. Thought by adding a high pressure gear lubricant this would silence the noise. Yes, in fact you can, in a manual trans. I replaced the trans. in my 88 Ranger, which used Mercon. The seals leaked in the old one, and because it relies a constant oil bath of Mercon, when you lose the fluid, you lose all lubrication. On the replacement trans., I used 80W-90, so there would be lube on gears even if fluid was lost. It does make the shifting slightly stiffer, esp. in cold of winter. HOWEVER, you might need to clean out all the old auto trans. fluid/Mercon before repl. it with 80-90, as I don't know if they would mix well or seperate. Probably wouldn't matter, but I don't know that for sure. BTW, heavy weight gear oil was used in man. trannies long before the 30W oil and ATF that is used in some cars/trucks now! PS- the sound you're hearing now probably means the input shaft is slightly off-centered when you put the seals in. If it doesn't shutter bad it should be OK.