DieselBD

Well I did my first ever front and back differential fluid change today. All went well, very easy but I took my time to make sure I did everything just right. No broken bolts which was my biggest concern.

One thing I can't get out of my head is the smell of the differential fluid!!! What is that? I detected a combo of sweet yet sour, a bit of garlic, perhaps an onion and maybe moth ***** along with the smell of oil. Next time, I think I'll run a fan behind me.

gunny

I'll give you some more advice on that oil too. It don't work so well for frying fish either, leaves a funny taste.

butchb

Try smelling the rear end or power divider fluid from a over the road tractor with about 700k miles on it!! I have NEVER smelled anything as bad.

VFDFireman

I don't know if this is still the case but most diff oils used to have a fair amount of sulphur in them.

I usually use medical gloves when working with gear oil as the smell stays in your hands for weeks if you don't.

Diesel Junkie

Usually used gear oil smells just like new gear oil, it stinks a little....

I used to work in a shop that installed lockers and ring and pinion swaps a lot.

If the used gear oil stinks up the whole shop, its usually beacuse it is BURNT.... If the gear oil has been overheated a lot it will stink for some reason, you might want to check the teeth for any odd wear marks or cracks, and the bearings if you can.....

Hard to believe you could burn up the Rear AND the front.... but just in case:

If everything checks ok, it is probably burnt cause of your driving and hauling habits... i would buy one of those super capacity diff covers and over fill the hell out of the rear end. you can fill more than 1/2 or 3/4 up the tube diameter no problem. more oil = more cooling, and the tubes have a lot of capacity.

redeyedracer

Actually over filling rear ends (or anything for that matter) usually causes excess cavitation which creates tiny air bubbles in the oils (also a loss in power). I believe that there is a TSB specificly for our trucks which warns about overfilling these AAM axles. The full mark for the AAM axles is actually 1/4" BELOW the fill hole.....

Names_TJ

I love the smell of gear oil! Especially in the morning! No joke!

drewp831

Just like an engine, if you over fill it you literally ruin your bottom end. Imagine your crank slamming into oil at 2.5K. Same goes for a diff. The bubbles it creates actually do much more harm than having the extra oil would/could benefit you.