Oddly enough I am even more confused than when I started reading this. Then again, I don't even know which tranny I have at this point. Hell, yesterday I had to google pix of the original gear shift **** to find out I had a 5 speed with reverse down and to the right. (missing shifter ****, so no diagram)

First I'll get it to run, then I'll get everything else ironed out. Once I do I'll be looking into changing all the fluids.

 

Reading through the FSM this is what I gleaned for my 1996 5 Speed .....

Manual Transmission:
SAE 75W-90 API Quality Grade GL-5 Gear Lubricant


Transfer Case ( 4WD ):
MOPAR ATF PLUS type 7176 0r equivalent Mecron/Dexron III ATF



Front and Rear Axles:

Normal operation:
Use SAE 75W-90, API Quality Grad GL-5 in all Jeep 4WD front and rear diffs.

Trailer Towing:
Use SAE 80-140, API Quality Grade GL-5 Gear Lubricant

XJ's with Class III Hitch use 75W-140 synthetic gear lubricant in the REAR axle



Now I read I can use 10W30 motor oil in the trans? Chrysler says this is OK?

So what API rating motor oil can I use?

So what API rating motor oil can I NOT use?


I want to change out the trans fluid SOON !!!!

 

I would use gear oil not motor oil, the detergents are going to be different and I believe viscosity shearing would be different as well. Viscosity can be the same at similar temps but each part is not going to run at the same temp.

API rating you should look for?? SL

API rating you should avoid?? I do not believe this is something I can really answer? The newer API ratings SM & SN should be superior to SL but Flat tappet owners preach that until further info is proven on the ZDDP levels we should stay with SL.

Hope that helps. I am by no means a professional but thought I would share at least what I know.

 

has anyone used synthetic gear oil in the 5 speed manual transmission?