I just replaced my differential oil today, and when I took out the drain plug the magnet on the end of the plug had so many filings on it that it looked like it was coated in about and 1/8" of grease. As I am back there watching the oil drain out of the differential you can see more metal filings coming out in the oil. I have never seen anything like this, is this normal?

 

I will let you know when I change mine - hopefully tomorrow. Was it a 10MM hex driver to get the plugs out? Did you replace your crush washers? My local dealership didn't have them in stock, and said they never change them when they do a differential service...

Also, what kind of replacement lube did you use? The Service Manual and Owner's Manual both specify 80W-90, but I want to use a full synthetic. My search at the local parts places this afternoon yielded only 75W-90 in Mobil 1 and Royal Purple. In the manual for my Q and my truck, there is a chart showing the acceptable types of oil in different ambient temperatures... and 75W-90 & 80W-90 are lumped together. I wonder if it matters?

Heath

 

it's normal...I just did mines @ 60k and same thing. If I knew this would happen, I would changed my diff. @ 30 or 40k.

 

that is the correct driver. just crack open the fill before the drain and it will come alot easier. it would also be bad if the fill had issues opening after drained it. i did replace my washers b/c they were in stock but when i was searching before it, many said they reused the original ones. i used the M1 75w-90 because it was readily available and many recommended it.

 

I'm glad to see that I'm not the only one, however, metal shavings never seem good to me

 

it wont be like that the second time you change the fluid. just the o.e. stuff breaking in.

 

correction, it wont be nearly as bad the second time you do a drain/fill. I did mine at 30k and had all the shavings and such (completely normal) and just did it again at 50k and had a little bit of shavings/grease on the magnet (also normal)

you DONT need to replace the washers. I've used the same ones (changed the oil twice) and all is well. Same with the crush washer on the engine oil drain plug, i've used the same one for the last 50k and never changed it and never lost a drop of oil.
-GP-

 

I had the same results as far as the metal filings. I wish I had drained it earlier... this was my first change at about 29K. After refilling the differential, I had a small trickle of oil running out of the fill hole and could still see some grey stuff in there.

I put in Valvoilne 80W-90 conventional oil, and I think I'll change it again at my next oil change. Probably with Amsoil 80W-90 (or maybe one more run of conventional oil first) if I can find it... I noticed a shop near my house with a big "Amsoil Sold Here" sign, so assuming their prices are pretty close to the prices in thier online store, I think I'm going to buy a gallon of their 80W-90 synthetic. I don't know why the G35 only specifies that weight, but I want to try it in my truck's manual transmission anyway... I have been having trouble getting with it not going into gear in colder ambient temperatures before the truck warms up.

Heath

 

Have you guys had any issues with needing an additive, aka friction modifier for the LSD?

 

The metal particles for the diff. are normal. I changed my trans. and diff. with redline at 70K.

 

Anyone know this?

 

It is a 10MM allen head bolt.

Heath

 

Reminds me, I gotta get busy and change mine. Going with Amsoil.

 

If you haven't done it before, I would go with a couple of standard oil changes to get all of the metal flakes out of there first. It's kind of alarming on the first drain - although everyone says the same thing, so I guess it's normal.

Heath

 

It's due at 30k normally. If you want to extend the life of the diff/ MT trans, drain & refill the factory fluids after they are broken in (about 3-4 k).