Gear Oil for T176 and Dana 300

[COCJ5]

I want to change out the Transmission and TC oil in the 83 CJ5 I recently purchased as I dont know how long it has been in there. I have conflicting info on going with mineral oil or synthetic. Cost is an obvious con for synthetic, what other considerations/recommendations do you guys have?

 

[ftwflh]

I run a good 80w90 oil and add some Lucas oil treatment to it.

 

[Old Dog]

I've heard people say they got leaks after changing to a syn. oil in older vehicles. Never happened to me though.
I use good old dino 80-90 in my Dana 300 , and it still leaks :laugh:

 

[COCJ5]

I've done a lot of research on this the last few days. Turns out that syncromesh transmissions like the T-176 really should have a less viscous fluid. I got that from Tremecs website and a few other references. Apparently the bearings need a thinner lube. I dont know what the owners manual recommends but apparently the 83s came from the factory with ATF in both the tranny and Transfer Case . Also you do not want to use a GL-5 gear oil because it is high in sulpher that will corrode the brass parts. It is getting increasingly hard to find a GL-4 rated gear oil. Think I am going to try Amoils MTF in the T-176 and Redlines GL-4 75-90 in the Dana 300 .

Rod

 

[ftwflh]

The way I see it when these things came off the show room floor they only had motor oil and gear oil so that is what I use.With the exception on Limited slip and locking difs.I am the same way with my old 1972 Harley.60wt motor oil and 80w90 in tranny.These older mchines dont like synthetic stuff.