[magnettarpit]

owners manual says use sae 80w-90.
walmart has sae 80w-90 GL-5.
I called 2 Ford parts departments and asked 'em what the difference was, and what does the GL-5 denote. Neither one could answer the question. Can one of you knowledgeable folks please?
thnx
mike long in addison texas usa

[RandyStinchcomb]

GL-5 just meens for use in Hypoid diffs, or a pinion gear that sets below the centerline of the axle....

[magnettarpit]

super, but is the sae 80w-90 gl-5 compatible with my stang? after all, the owners manual calls for sae 80w-90,not sae 80w-90 gl-5.

thnx again
mike

[RandyStinchcomb]

Originally Posted by magnettarpit

super, but is the sae 80w-90 gl-5 compatible with my stang? after all, the owners manual calls for sae 80w-90,not sae 80w-90 gl-5.

thnx again
mike

yes, SAE 80W90-GL5 is fine, just about all rear gear oil today is GL-5 rated

[magnettarpit]

Thanx man!
mike long

[kmyers]

I just changed my differntial oil yesterday and I used 75w-140. On my differntial there is a tag that says use 75w-140 ONLY. I also confused to because I have a Haynes manual that says 80w-90, but I called my brother who is a Ford mechanic and also owns a gt and he said use the 75w-140. Just putting in my two cents.

[RandyStinchcomb]

Originally Posted by kmyers

I just changed my differntial oil yesterday and I used 75w-140. On my differntial there is a tag that says use 75w-140 ONLY. I also confused to because I have a Haynes manual that says 80w-90, but I called my brother who is a Ford mechanic and also owns a gt and he said use the 75w-140. Just putting in my two cents.

you can use either in the diff, 75W90, 80W90 or 75W140....some Ford car's & truck's Will Have a second tag on the rear cover stating the use of 75W140 in the rear diff....... personally, I dont like the 75W140 in the rear diffs, I've seen some very early rear carrier bearing failures on car's & truck's that use this fluid......