Quick T-case question

[cummins king]

i drained the t-case oil for the first time since i owned the truck, and it came out looking pretty good, with minimal shavings

questions is what oil do you guys like to use?the same stuff that goes into the rear ends ?

thanks
Joel

[bgilbert]

Yes gear oil, gear driven cast iron case = gear oil. Chain driven aluminum case = ATF. 80-90 wt will work fine. I don't think there's a need for 85-140 unless you're towing heavy frequently. In my experience synthetic = leaks from output shafts on t-case, where they didn't leak previously .

[nooblet]

x2 i use 80w-90

[cummins king]

thanks
joel