I changed my diff fluid on my '02 several months ago at about 7K miles, and it was NASTY. The magnetic drain plug had shavings all over it, and the used oil was really black, smelly and thick. I replaced it with Mobil 1 Gear Oil 75W-90.

I just reached 19K miles, so I decided to change it again. I was REALLY surprised to find that the used oil was pretty damn clean, and had no odor. It was nothing like the last change, and there was only a slight buildup of shavings on the drain plug.

Now, I am starting to think that either the original oil was just very different from the Mobil 1, or the break-in of the differential really fouls the oil. I wish I had changed the original oil sooner, and waited longer to change it the second time.

Have any of you noticed this?

 

I noticed the same thing.

I changed the original around 7k as well (to Redline 75W-90). Since it was so nasty I changed the oil again at 12k before I sold the car and it was clean as a whistle.

Side note... I changed the original tranny fluid out as well at 7k miles and it was pretty clean.

 

Yes, with the first change, I thought that the differential was going to wear itself out with so much metal debris on the plug. Each subsequent change showed the fluid to be cleaner and the plug with progressively less metal shavings such that I am not concerned about keep the fluid in for longer periods.

 

I changed mine quite early in the car's life and the same thing here although not as bad as gernby's case since he tracks his car. Each subsequent time, the oil didn't look as bad. I have over a 1000 miles on my new rear gears and will be changing that soon as well.
I think everyone should consider changing out the diff fluid after the gears have had their break in time.
I'm about to change out the fluid for "Former" in about 30 minutes from now. He drives his car fairly "sedately" and he's got something like about 10K miles and this will be the first change. I'll report back this afternoon to tell you how it looked.

 

Just finished the fluid change. I took a couple of blurry pics but I think you'll get the idea.
The first one shows the oil drain plug right after it was pulled out and before it was wiped. It has about 3-4mm of magnetized sludge stuck on the end of it.

Now you see it after it had been wiped clean. What you see on the bottom white tissue was from the first swipe. The other tissue finished it off and you see the cleaned plug.

The fluid that came out was pretty cruddy looking but not at all unusual compared to when I did mine at about 2000 miles. I think most of the wear comes in the initial break-in phase.

 

Thanks to the "guru" the diff change was smooth as always. I had 10K miles with zero clutch dumps and fairly easy driving.

The old fluid was thick and purple and the plug had a lot of fine sludge shavings. If you care about your drivetrain, have it changed after the first oil change.

 

I am curious how many of the failed differentials (on non-FI cars) had original oil in them.

 

THIS would be a REALLY good question for which the answer would be most interesting.

 

Thanks for the info, Gernby. I was hoping that Mobil-1 would last a good 15,000 miles between changes.

I'm glad I got the OEM stuff out of there!

 

[QUOTE]Originally posted by Destiny2002
[B]Thanks for the info, Gernby.