I replaced the factory fluid at 18k miles and the original fluid was fairly opaque/greyish in color when it was drained. The drain plug had silver sludge on it but no chunks of metal was drained. From what I have read, this is normal. Refilled the diff with Mobil 1 75W-90 and drove it for 1k and did another drain. To my surprise, the fluid came out looking the same as the factory fill, greyish/opague. Refilled it again using amsoil severe gear 75W-110 and drove another 1k and drained it. The amsoil was not as bad as the first 2 changes but certainly had a greyish hue to it. Refilled it with amsoil 75W-110 and drove it for 3yrs/4K miles. This drain was much better but again, had a very slight greyish/opagueness to it. Drain plug again had greyish/black sludge but no metal chunks or large shavings from what I can see. Is this normal? My car is now sitting at 24k miles and been through 3 diff fluid changes. While the fluid is coming out cleaner with each change, it also has a varying degree of "grey" to it. On the contrary, the tranny fluid, each time I change it, comes out looking the same as it went in. Nice and clear. I just want to ensure that my diff is not on its way out.

Thanks.

 

I would think the grey color is just residual fluid getting mixed in the bunch. I always use le1605 so it comes out red but the 1 time i used redline fluid because I wasnt able to order the le1605, it came out red from the leftover le1605.

 

The original run is going to have the highest wear metals from break-in if not changed early, that is going to take a few drains to fully release, could have been a bit of sludge in there too. Your current drain should look better on the next drain. Diff temps can be higher than tranny temps, with higher wear metals, and the sump capacity is much smaller. The metal paste on the drain plug is normal and will always be there on each drain.

 

I do a 50/50 mix of M1 75/90 and 75/140. Put 30k miles on the diff fluid and drain, have 120k miles on my '06 and I get next to no metal on the drain plug. The color of the diff fluid looks much like new when drained, just a shade darker.

ROD

 

Just changed my diff fluid after ~2 years and 20K miles, previous owner had Mobil1 75w90 and I put in the same. A little metal paste on the drain plug and the fluid was a shade darker than the new stuff I was putting in.

 

Thanks guys. I will change it out again next summer and monitor it then.

 

I got my 01 last summer with 19K miles on it. I drained the diff and like you noted the oil that came out looked awful. I refilled with Mobil 1 75W-90, drove a few hundred miles, and drained it again. Like you, that drain was only marginally better. It took 3 drain/refills before the oil came out clean and clear.

Bottom line, I don't think the type of oil has anything to do with how many drain/refill cycles it takes to get clean oil. It's just going to take a few times to get all the crud out regardless of what oil you are using.

 

Stop wasting so much oil guys!

Unless you're launching the car all the time, fill it up with at least Mobil1 75w90 and stop worrying -- a little paste is normal

LE 1605 is supposedly the best, followed by Amsoil, but I've been happy with my cheapo M1 75w90 for YEARS. And supposedly it's what Billman fills all his customers with