Posted by Louie65 on September 22, 04 at 12:48:56:
I was topping off fluids and noticied that the differential was low (previous vehicles recommended fill to the bottom of the fill hole). I had some 80W90 dino oil and topped off with it. Later, I checked the owner's manual and discovered that it requires 75W90 synthetic. Should I be concerned and drain/refill with the synthetic or is O.K. to leave it as is. In addition, the manual says refill to 5/8" to 1 5/8" below the bottom of the fill hole. How does one measure that when I can barely fit my pinky finger in the fill hole? The manual did not give an exact amount in pints/liters. My vehicle is a 2003 GMC Yukon XL (C1500) with a 10 bolt differential, limited slip, 3.73 gear ratio. RPO codes GT4, G80.