RallyXAudi

I think I may have f'd up. Last night, I changed the oil in both the rear diff, and the transmission. I used gear oil rated for GL3, GL4, and GL5, and after reading some of the older threads here, I think that may have been a bad idea. The bottle reads API SERVICE GL5, GL4, GL3. I have only driven back and forth to work once. Should I drain and refill the trans with oil rated GL4 only? And is the rear diff OK with the multi-rating oil? Also, the Bentley lists the rear diff capacity at 2.2L, but I was barely able to get 1L in it. It was far more than was in there before, but still way off of what the Bentley is telling me it should take.

CGTBrad

IIRC the word on the street is that it will corrode your synchros. Get yourself some redline!

sagjohnson

I'm about to do mine and bought that for it. Planning to do tomorrow.

mt6127

The rear diff only as steel gears so it can use a GL5 of proper weight. These are pretty easy to find at your local Walmart. For the tranny, Audi recommends a GL4 - the main reason to avoid GL5s is that the tranny has brass synchro rings which don't agree with some of the compounds which may be in a GL5. Redline and Amsoil make Synthetic GL4s which are perfect for the Audi tranny. Don't worry about having the GL5 in there short term - what I read it that it can cause premature wear after 100K miles - not that you'd see liquid brass when you drain. Also, not all GL5s are the same. Moly's GL5 is sold for Audi's with no suggestion of issues. When you get the chance order up some Redline and throw in a couple of liters of MT90...<ul><li><a href="http://www.myoilshop.com/AutoPrds.html">Redline Oil</a></li></ul>

CGTBrad

That's exactly what you need to use Chris! You'll be amazed by the difference!

sagjohnson

<center><img src="http://pictureposter.audiworld.com/10657/109.jpg"></center><p>
I went to my trusted shop and they gave me this after I asked for MT-90. Will this stuff work:


75W90 NS

This GL-5-type geal oil doesn't contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting. Can also be used in racing limited-slip differentials where weak spring design causes too much wheel spin.