RBA

Questions for those who run it. I will be using the mt-90 on my 5 spd transmission but could I use the same for the transfer case and differential or do I need to switch to the 75W-90 gear oil for those? Thanks for the input.

Keith B.

MT90 is GL-4 spec: good for trans and tfr, but diffs require GL-5---75W90, 80W-90, etc. Hint: If you are daily driving in 2WD(like most of us), change rear diff oil more often, even with sythetic GL-5.

MMA_Alex

Aren't a whole lot of people running mt-90 in the t-case, but it should be fine. You'll love it in the trans. Its like night vs. day when the trans is cold.

Matt16

I put MT-90 in my transmission and it truly is night and day. Could be my imagination, the full benefits came after a couple days.

Before MT-90 it was hard to engage 2nd gear often. Afterward it felt butter smooth. One of the best mods I've done.

MMA_Alex

For me it took a fair amount of force to get it into 2nd on cold mornings unless you drove in first for a mile or two to let the oil get moving. With the mt-90 it goes right into 2nd even when cold with no issues. It also shifts smoother than before, but its way more noticable when cold.

and yeah im sorry i missed the diff part of your question. the gears in the diff are under more pressure, and so you want a gl-5 (extreme pressure) lubricant.

Matt16

wonder what's up with second eh?

MMA_Alex

im guessing syncro wear since 1/2 are the most used gears, but generally you're not moving when putting 'er into first

Squeebs

Amsoil severe gear 75-90


and then forget about it.