Crenwelge, thank you for posting that link. I found it inconclusive because it does not go into depth about the interaction of "yellow" metal and GL-5. I would like to know what actually happens, under what conditions and how long it takes.
On a Sta-Lube GL-5 SAE 85W-140 container I have the following is stated."For complete fill or topping off of manual transmissions, hypoid type differentials, limited slip/twin grip/trac-loc/sure-grip differentials where 85W-140 grade is recommended"
On a Valvoline GL-5 SAE 80W-85W-90 container I have the following is stated. "For use in manual transmisions and in both regular and limited slip differentials"
That suggests that GL-5 IS OK for manual transmissions.
Can a lubrication engineer or chemical engineer shed some light on this for us?
