Getting ready to put the motor and trans back in the 84 Cav. The GM shop manual calls for 5 w 30 in the 5 spd trans, is it OK to use synthetic oil?
Well I guess you could use the synthetic if you wanted.But being the age of trans and switching from conventional to synthetic you may not see any real benefit.However it may assist in cold or hot temps no doubt.Personally my old cav had the 5w30 stuff and have two manuals one says dex 3 and other 5w30 can't recall my owners manual.But I changed over to dex 3 bc it is more fluid like especially in cold and shifts better at least to me.If I were to run oil I use conventional bc the trans may(or may not) burn the synthetic bc of it's age of the trans cars are fickle about changing between the two.Soley your choice and it will not harm it,just my take on swapping fluids as such.Granted I had zero problems with my dex 3 aside from my seal leaking at the input shaft and have new axles and seals both sides to replace prob this winter is when I will jump on that.Your pick on choice.R
