Hi, all!

I am getting ready to change my diff and tranny oils (2002 WRX with 33Kmi).

I decided to go with Mobil 1 75W90 in the rear diff and Valvoline (regular Dino) oil in the tranny / front diff. I heard that synthetics make the synchros too slippery if used in the tranny.

The only problem is, my local Pep Girls only carries 80W90 oils... Is it OK to use these, are they better in hot weather (100+) than the 75W90? Should I try to get the 75W90 instead of 80W90, as specified in the manual...

Thanks for the input!
Maniac.

 

bum...p!

 

Do not use mobil 1 what ever you do. That is what i am using and it truly sucks. My tranny is all messed up now because the synchros are gone and my rear diff isn't tranfering properly because the oil is to slippery and not viscous enough.

 

The mobil 1 should be just fine in the rear diff. - for the transmission, you will be just fine with 80W90. (based upon posts here and in other forums, there are some dealerships which use 80W90 when they service the Impreza, anyway) - the oil will be a little thicker than a 75w90 when cold, but will be the same as it warms up to operating temperatures.

Mobil-1, and a number of other synthetics, have caused some people trouble in the transmission which has been attributed to the oil being too slippery for proper synchro function (others have used Mobil-1 in the transmission with no problem) - the more slippery oil will be just fine for gears, though - so the rear diff won't be a problem (the limited slip portion is sealed, so the gear oil is just to protect the gears, not the part which needs some friction)

 

ahh...good to know

 

Thank you guys for replying to my question in such thorugh informative manner!

I'll be getting some 75W90 Dino Valvoline today!