Posted by Louie65 on September 23, 04 at 01:44:35:
In Reply to: Should I drain differential after adding dino oil to the synthetic? posted by Louie65 on September 22, 04 at 12:48:56:
Thank you everyone for your advice. I didn't mention prior that my vehicle has 18k miles and not used for towing. The allen wrench worked great! Even with the topping off, the level was at 3/4" below the bottom of the fill hole.
I decided to drain the differential anyway heeding Traveler's advice. I had not serviced it prior and the break in metallic particles was a concern. There must have been a solid 1/8" of metallic sludge particles stuck to the circular magnet affixed to the inside of the rear cover. This caused me to wonder further and I took a second look in the owner's manual. Not once is it mentioned to change the gear oil from the 7,500 through 150,000 service check list. It always says check and add fluid! I thought it strange that GM couldn't publish the accurate amount of gear oil to refill the differential in the capacities section. The average individual won't be sticking allen wrench keys into their fill holes and then comparing it to a ruler to obtain the 5/8"-1 5/8" below the bottom of the fill hole.
I used 2 quarts and approximately 10 oz. to achieve a level of 7/8" below the bottom of the fill hole. Bought the Mobil-1 synthetic for $6.99 quart at the local AutoZone store. Lastly, my 1994 Chevrolet C1500 pickup requires (per the owners manual) that the differential be filled to the bottom of the fill hole. Has GM realized that this overfilling has caused seals to fail? My rear axle seals failed at approximately 75,000. Could this overfilling have contributed to it?
Thanks again and keep up the good work!!!