Final Drive gear oil question

[Muleears]

I have drained the final drive, knowing I had oil to replace it. I then realized what I have is two bottles of Mobil 1 gear oil, one of which is a 75-90W GL-5, the other a 75-90W GL-5 with the limited slip friction modifier. Questions are: Can I use 75-90W? Manual calls for 80W. Second question: Should I use the one with the friction modifier or without? Any help is greatly appreciated....My baby is sitting in the driveway with no oil in the final drive waiting for some knowledgeable soul to fill me in on these simple questions.

I know not to fill it "full" but instead leave it about 1/4" below the edge of the fill hole.

[doug of so fla]

Either one would be fine.. imho..

[Muleears]

Thanks Doug. I already put the regular Mobil 1 in. I figured if someone else told me not to it is easy enough to change back.

Color somewhat concerned me though. The old oil looked clear coming out but as it collected in the container it took on a definite gray color. I doubt it has ever been changed, so some color after 22K is probably ok. What do you think?

[doug of so fla]

Yes, you will get some color (wear) Some use a magnetic drain plug and it collects the metal grit so you can see it and should help keep it from wearing more. I used "Golden Spectro", Lube Full synthetic GL-5, and it it was the same color after 25,000 + mi. I think it is a great product but very expensive to use, but for rear end you do not need much so it does'nt amt to that much.. a qt will last longer than me!!!

[Muleears]

Yes, you will get some color (wear) Some use a magnetic drain plug and it collects the metal grit so you can see it and should help keep it from wearing more. I used "Golden Spectro", Lube Full synthetic GL-5, and it it was the same color after 25,000 + mi. I think it is a great product but very expensive to use, but for rear end you do not need much so it does'nt amt to that much.. a qt will last longer than me!!!

Thanks again Doug, that sounds like good advice. I imagine what I just drained was the original fill and probably not synthetic. Now it has Mobil 1 full syn in it and should be good for a while.

Where can I get a magnetic drain plug?

[HawkeSHR]

How long between final drive gear oil changes is recommended (just being lazy here before I go to my books)...?
Thanks for your response!