So I did my own fluid change on the diffs. Followed the instructions and write up on Project JK. Got four quarts of oil for em and drained em completely but when I filled em back up it only used a two and a half quarts total for both diffs??

This sound right?

Everything seems to be running fine and no noises...

 

Here are the factory differential capacities for the JK:

FRONT AXLE ± .03 L (1 oz.)
186 FBI (Model 30) 1.0 L (2.1 Pints)
216 RBI (Model 44) 1.3 L (2.7 Pints)

REAR AXLE ± .03 L (1 oz.)
198 RBI (Model 35) 1.83 L (3.8 Pints)
226 RBI (Model 44) 2.25 L (4.75 Pints)

Actual amounts from factory on my vehicle:
Front Dana 44: 44oz (15oz above bottom of fill hole)
Rear Dana 44: 72oz (slightly above bottom of fill hole)

 

That sounds a little low. Do you have a Rubicon? Are you lifted significantly? Stock diff covers? When I did mine, I got two quarts in the rear D44, and one in the front D30, bone stock.

 

Nope Im a totally stock X, auto. So you got half a quart more than me..

 

That's weird. I bought 3 quarts of Mobile 1 and used virtually all of it as I described.

 

How are you determining that they are "full"? Are you filling to the bottom of the fill hole? I don't think that works with these. My understanding is that you're just supposed to fill with the recommended amount. I've seen some where you even have to jack up one side so that you can keep filling past the fill plug. It ain't about the bottom of the fill hole anymore......us old school boys ain't used to all this stuff.

 

I just did mine today as well, by the right up and i only one 1qt in the front and 2qt in the rear and i filled them until both where over flowing. So i was going to run it today and check it tomorrow.

 

did anyone every really answer this?

 

1 QT in the front (D30)

2 QT in the rear (D44)

 

the dealer told me today that you needed to put in some kind of additive into the gear oil... one bottle in each diff... $16 for both from the dealer.