My rear diff cap is supposedly 3.06 qts but its taken 3.25qts+ and still not ovrflowing at fill plug

Is this normal? Should i contine to fill until it overflows at the fill plug or take some out until its at the 3.06qts fill rate?
The vehicle is on a level surface with oem suspension and wheels.

 

Keep going if you wish. Correct oil level is bottom of fill hole max.

 

No question for me, I would fill it till it runs out.

 

is your truck level?

 

Yes its level

 

I'd be more worried if it took less. Fill it to the hole.

 

Fill it till the hole is dripping.

 

Thanks everyone.
Will the same logic apply to the transfer case too? Its capacity is supposedly 1.08 qts .

 

Like everyone said, just make sure the truck is level

 

Yes...t-case, diffs and manual transmission get filled to the fill port

 

Now would be a good time to check the vent

 

Roger that eon blue, thanks.
Heading back to the store for more gear oil.

 

10MGM
What vent are you talking about? I'm a novice at this stuff

 

Diff vent is on top of axle housing. Looks like a nipple. Remove with open end wrench. Check that air can flow through vent and check that the threaded hole in axle housing is not plugged.

 

Don't forget. Level means not only front to back, but side to side too. Oil may rise up and fill an axle tube.

 

The oil also could be going out through the seals in the back of the rear brakes.

 

T case, front and rear diffs all filled to the fill hole. No leaks anywhere, drives like a champ. The old oils were still in pretty good shape but better safe than sorry with fresh oils after putting on 30k, some of which has been mountainous towing.
Easy job even for a novice, can't see how dealerships or lube shops can charge consumers so much. Thanks everyone.

 

They charge that much because people will pay that much, because they aren't willing to do it themselves. Like you did.