100,000 Mile service

[The Lurch]

Well, my '01 GMC Duramax is about to roll 100,000 miles. I want to change all the fluids in the truck. What I need to know is how much coolant and gear lube the truck takes.

Also, if there are any special techniques to making the change, any advice would be grateful.

One last thing.... Is it worth putting synthetic in both differentials?

[Heartbeat Hauler]

I believe the Duramax/Allison manual says the radiator takes almost 22 quarts, but I'm not sure if you can get all of the old stuff out when flushing...some may stay in the engine.

I don't know about the diffs for sure, but I think it's around 2 or 3 just for the rear, and the front takes less. If you aren't gonna run GM oil in the diff then yes syn is a must in the rear...just make sure it meets GM specs GL-5....forget the GM#. Also, if you switch to syn in the front there is a breather cap that needs to be replaced.

Also, if you haven't done it, flush that break fluid, replace spin-on trans filter & oil, and don't forget the transfer case if you have 4wheel drive. You are probably also due for in-cab air filters lcoated under the dash on the pass. side...gotta remove the cover.
JP