T-18 Transmission oil question.

[Tom@Hilltop_Machine]

I would like to change the oil in my 1972 transmission. I know it calls for 80-90 weight GL3 oil. Well GL3 oil has been replaced by GL4 and there is even GL5 oil out now. The internet Gods say not to use GL5 gear oil because the additives will attack the brass metal sync rings. GL4 is "Okay" as a replacement. GL3 is impossible to find so what are you guys using?

 

[jeepinmatt]

https://www.napaonline.com/en/p/NHF65201

Maybe?

Or here is some GL-4 stuff:

https://www.napaonline.com/en/p/SL_SL24229

 

[skyhighZJ]

Amsoil still makes GL3 it’s what goes in my NV4500 behind the 12 valve Cummings order off their website direct and it’s a pretty quick ship. I think mine was to the house in like 3 days (ground). Redline also makes a GL3.

 

[NickMaul]

Redline is the bees knees

 

[Blue CJ]

Synchromesh works great.

 

[Caver Dave]

I'm sure whatever's in there now will be fine (sitting in the shed another 4-5 more years)