MT Transmission/gear oils for the 90 pickup

[Legacy777]

I'm going to be doing some work on my mom's 1990 pickup. One of the things I want to do is change the oil in the transmission, transfer case, and front & rear diffs.

Has anyone found any particular gear oil that works well or doesn't work well?

I know on my subaru some gear oils make the shifting pretty bad.

Other thing, I know the manual states to use GL5 gear oil for the differentials and transfer case due to the hypoid gears.

The manual states you can use either GL4 or GL5 in the transmission. If there are no hypoid gears in the transmission I see no reason to have the EP additives in there which can be tough on yellow metals (synchros).

Any comments would be greatly appreciated. I believe the oil that's in there is still from the factory......

Thanks
Josh

[qsd-dan]

Hi,

Last time I changed the trans and diff, I used mobile 1 synthetic 75-90. I could not belive the difference!! The trans shifts even smoother and I no longer have a problem with 2nd gear grinding when cold. Give it a try and post your results.

Dan

[Legacy777]

Thanks Dan for the comments.

I'm planning to do the work in another week or so, so that info is good to know.

Josh