Originally Posted by Amopower
Some of you may think this has been beat to death already, but after reading endless posts I am still not certain on which oil to buy for the *front* differential. Alldata says the front takes SAE90, and the rear takes either SAE90 or 85W90.
When I look at the car manual they make no distinction between the front or rear, says 85W90.
So two questions -
1. is the 85W90 OK for the front and rear?
2. Mobil 1 75W-90: this has also been debated before and I think the answer is that MB changed their original requirements to allow this, is that right? I already bought the 75W-90 after reading DETANE's DIY, but afterwards I saw some posts that debated his choice in using this.
1. You can use same front and rear.
2. I don't think you are going to do any harm using M1 75-90 unless you are doing some heavy duty towing or equivalent. The lower number is the weight when colde, and I don't think a lighter weight will hurt (although MB must have had a reason for the spec). If you can get the cold specs of what MB requires and measure against the M1 spec, you would have a pretty good idea.
I recently (6 months ago) had work done on both diffs, we used M1 75/90 from my long time MB indy mechanic (who spents years at a dealership) and he had no issues using M1.