As a preventative maintenance thing I am going to drain and replace my rear diff's gear oil and was wondering which oil does everyone recommend? I read this DIY http://www.audiworld.com/tech/misc33.shtml and they mentioned Royal Purple 75w90. I've always heard good things of RP but wondered if its worth it or is there a better choice out there.

 

I've been wanting to change mine too. The problem being is the rear calls for straight 90 weight synthetic in my book. But all I can find is 80w90 regular or 75w90 synthetic. I was thinking of going the Lucas 75w90 and adding a stabilizer with it to thicken it up a little.

Good Luck...

 

I use mobile 1 75w90 . woulnt touch RP if it were free but that's just my opinion from reading the bob forums. 75-80w-90w won't hurt it. it's 90w anyway after a couple miles. the 90w is hard to find so it's rpballt just one of those things to get you to a dealer

 

+1 i ordered the good stuff online for my front differential and totaly forgot to get extra for the rear. mobil 1 was the best i could find at pep boys so thats what i used. seems to be running smoothly.

 

I tend to change mine out every 60K miles. I'm now over 200K and no noise.