Ok guys so I've heard many different opinions on over filling diffs with too much oil. I've heard from many that it causes problems with the seals if you over fill and of course there are many that say that is a myth and there is no problem with over filling except a mess. I just replaced my covers with solid covers and I put 2 quarts front and rear. The front threw up out the breather and the rear is fine, but what I want to know is: Can overfilling your differentials with too much oil cause any seal problems or any other problems?

 

Bump....I know someone has to know?!

 

x2 I need to know also... I have the
Solid cover too. Thx

 

Mine came from the factory overfilled quite a bit. Never had a problem.

Is the fill hole on your new cover at a different level than the original?

Here is a pic of what the level should be, no matter where the fill hole is located.
The oil must be high enough in the rear to flow out to the wheel bearings in the rear axle, and high enough to get to the carrier bearings in the front axle. The picture is of the rear, but the front is the same.
So, if your new cover has a higher fill hole, the fluid needs to be only as high as the original hole was.
You can make a little dip stick to check.

 

Thanks. What can you use to make a dip stick? I was told that too much oil bubbles when there is too much and causes the seals to leak and then fail?

 

I had no ill effects when mine was overfilled. Others have had problems.

A zip tie makes a good dip stick for the diff.

 

Thanks! That's a really good idea with the zip tie!

 

Anyone else hear of any issues?

 

Anyone? Bump.

 

I don't know why the seals would fail--it's not a sealed system so there's no pressure build-up against the seals. I don't even know how that rumor got started--I've never read a first-hand account of overfilling a diff causing seal failure. But, I've first-hand experienced what happens when you get the diff overfilled--it was several months after servicing it. I was driving through a very hot Tucson--113 degrees or so. The next day in San Diego I had diffy fluid that had bubbled out of the top of the vent tube. I speculate that the oil will get a bit whipped up if the diffy is overfilled--at least that is what happens in a crankcase. Throw in high heat and there is even more bubbling. And bubbles do not lube the same as liquid. So, there may be long-term issues there--but failed seals? Never have seen any evidence of that.