case of the disapering rear diff oil

hi

2006 gmc sierra 1500

5.3ltr

4x4 z 71

i noticed on my bi annual check over, that the rear diff was was low about one quarter to has a liter.

checked the axel seals pinion seal diff cover.
No leaks!!

topped it up and took it to the dealerrship.

They could not find any leaks what so ever. shook there heads and never saw anything like it.

Took the cover off and replaced the oil wit Royal purple and a month later down a quarter to half liter.

This oil is all synthetic as required in the manual. 75 90

dumped that oil out added 80 90 dino oil. Month later down again the same amout.

Dealer is stumped. Maybe someone has had this same problem and solution.

Other than replacing the dif.

Thx in Advance

The only other place is the vent tube, if equipped. That's a stumper, for sure.

The only other place is the vent tube, if equipped. That's a stumper, for sure.


Thx for the reply Blue Bowtie

The vent hose is also dry and clear or gear oil.

I guess the only solution i have is to simple check accordingly and top it up.

Thx Again

Losing about a pint a month is not right. If it is not evaporating (do you regularly drive to the sun and back?) it MUST be going somewhere. One would think that there would be a trace of it somewhere, such as the brakes, undercarriage, etc. Obviously, it will need to be monitored and replenished until it is resolved. Hopefully, a trace of it will appear somewhere and you can find the leakage.

Good luck, and keep it full.

thx

Did you remove the rear rotors to check the axle seals, this was a common source of leaks on those trucks.

Did you remove the rear rotors to check the axle seals, this was a common source of leaks on those trucks.

Yes. Completely dry around the axles. Dealership and local shop said that was a common place to leak also when they checked it over for leaks.. I even threw a set of jackstands under it and checked myself.
No sign of any oil anywhere. Rusty and dry
109 490 kms on truck
thx