Synthetic 4WD Front Axle Lube & Cold Climates

[More Power]

GM began recommending the lube used in the 9.25" front axle be changed to synthetic in all 4WD 2500HD/3500 trucks sold or driven in cold climates like those found in Alaska or the colder regions of Canada. It's likely all 2003 or newer 4WD trucks were equipped with synthetic from the factory. I'll tell you how to check further down in this message.

GM has indicated that the mineral based lube used in the front axles of these vehicles may not lubricate properly at -12

[GMC Driver]

Is this a GM service bulletin, or something I should make my dealer aware of? And would it be covered by warranty? I'm not in the cold part of Canada, as it's about -14 C outside (5 F).

[More Power]

The above message was based on a GM service advisory. If you live or expect to drive in a cold environment meeting the above temperature range, your dealer would likely do this for you if you're within the 3/36 warranty period. I haven't heard how dealers are treating this sort of service work, but I imagine GM would rather pay for the fluid change than pay for repairing the front axle under warranty.

I live in Montana, where it can drop below the stated temps. I've not gone to synthetic lube... yet.... This'll be the 4th winter.

MP

[SDakDmax]

I put mobil 1 75-90 in the rear diff. Would that work fine in the front also? Thanks for the great info..

[4diesels]

75-90 is the correct oil for the front diff. I could have sworn though that the rear takes 75-140?