I noticed a slight squeaking noise on my 99 1500 when driving slow- went under to check u-joints & noticed some fluid leaking out of the rear diff. Turns out it was coming out past the plug- I pulled the plug off (breaking it- a plastic plug?) and fluid POURED out of the diff. I have not worked on many differentials, but from what I know the fluid should be below that hole. I checked the manual & confirmed that on the Dana rear fluid is supposed to be 3/4 in below hole. I can't figure out how it could even be filled that much. The last thing I want to do is screw this thing up, but I would like to drain & replace the fluid. Can someone recommend a gear lube and additive other than MOPAR? No dealer nearby. BTW- u-joints were tight- could the overfill pumpkin be the cause of the squeaking noise?

 

Possibly... Kinda doubt it though... Bearings failing is common on those 1/2 tons. Not sure how they filled the diff that much. But a lot of people are stupid.

 

I don't see how someone could have filled the diff that much. When you checked it, was the truck sitting for awhile, or did you drive it shorty beforehand?

You can get gear lube at any auto parts store. You want 75W-90 type GL5 lube. If you have a posi rear, get some friction modifier too.

 

Truck was sitting at least an hour. They must have used a d@mn turkey baster or something- it was loaded. The truck has a limited slip. I was thinking about switching to synthetic- will I still need the additive, or is the synthetic alone enough?

 

Ok, if it was sitting awhile, then they just overfilled it somehow. When you pop the cover off, this is a good time to check out the gears for any abnormal wear, chipped teeth, etc.

Switching to a synthetic is a good idea. I believe that most synthetics these days have a friction modifier in them (I know Mobile does), but read the bottle to make sure. It might not come right out and say "Has friction modifier"...it might say something like "Formulated for limited slip rear ends" or similar.

 

Will do- Thanks for the info!