I was at the dealer today and I asked the service writer how much was it to change the rear diff. lube and, he told me that after the first 5000 miles they do a complete flush to get rid of any small metal particles and fill it with gm brand syn. lube. all ths for $110.00:eek:

My question is would changing it at home be the same as the dealer? I see alot of members on here doing it themselves and it just a waste of $$ to have the dealer do it??

thanx..........JLew:D

I think most of the cost of having it done at the dealer is they use the factory "grape juice" which is $20+/quart. I think the majority of guys just use a GL-5 rated synthetic gear oil such as Mobil 1, Valvoline, etc. gear oil and do it themselves. I've done it twice myself for less then $40 and it takes about 15 minutes. I spent an extra couple bucks and bought one of those screw on push style pumps with a clear hose that you screw onto the quart jugs ...makes refilling much easier as their isn't a lot of clearance to turn the bottles up right to get all the fluid out. Pumping it in makes it much easier.

I don't know how they flush it but a drain and fill is enough. It's as simple as removing a drain plug.

Plus it doesn't take anything other than a 3/8" ratchet to remove the plug. Go get yourself 4 quarts of a quality syn lube rated 75w90 or w140 if you tow a lot and do it yourself. It's a 20 minute job tops.

Why is the grape juice so expensive? What does it contain that other synth 75w90 oils do not? Just curious as I just picked up my new rig and need to change the rear fluid. I don't want to skimp on a $30k truck, but at the same time, I don't like to waste $ either. Is Valvoline, Mobil or Amsoil "good enough" for the G80?

Thanks

Not sure why it's so expensive ... perhaps because it says "GM" on the label ...and smells like grapes. IMO as long as the gear oil has the required GL-5 rating ...that's enough for me ...their all equal at that point ...aside from the color/smell.

You are paying for their parts mark-up and Labor. Some people don't mind paying the dealer, as they have no or little mechanical skills, and don't want the mess and the hassle of disposing of the old fluid.

I'd actually change my own fluid, but could buy the grape juice from the dealer to at least save the labor $'s. Just wondering about the cost of the product itself. $8 at Schucks vs $24 at the dealer?

Tophog, sounds you don't run the grape juice. Any probs so far?

I've got 6000 miles on my rear diff since I switched to amsoil severe gear (75w-90) and it's been running just fine.