The Tcase takes the same fluid as is in the tranny
We swapped out our large air compressors and several other machines over to Amsoil at work, after reading up on it I change my whole truck over to Amsoil, tranny, T case, both diffs, engine oil and filter.
About 8,000 miles later the tranny died, about 10,000 miles later I had to rebuild the engine.
Around that same time we started having problems with the machines at work that we changed over.
Not saying Amsoil did it, I still think Amsoil is probably good stuff, just saying I’m very unlucky like that.
That was about a year ago, the wife’s jeep is still going strong on the complete Amsoil changeover but my PSD didn’t fare as well, only the diff fluids are still filled with Amsoil. I think all of the machines at work have been changed over to Castrol fluids.