Changing Fluids

[ChriSS K]

Just wanted to get everyones take on the maintenance fluid changing. I know there are many school of thoughts here. I have an 08 envoy denali with 43K on it. I know I'm going to be hearing from the dealer soon about how I have to change trans fluid and stuff. Whats the rule here? I can tell you right now that the fluid is just as pink as it was with 10K on it. What fluids do you guys change and when? With the exception of oil. Thanks

 

[tblazerdude]

I can not speak for what a GM dealer would say, but here are the intervals I use;
Transmission pan flush every 20k (I have a drain plug, so it's as easy as changing engine oil, also the pan holds 1/3 of the total capacity so in theory after 3 changes you end up with mostly new fluid, and after every third flush I drop the pan and put in a new transmission filter). Coolant, front and rear differentials, transfer case, and power steering every 50k. Brake fluid every 100k. I think that's all the fluids in the truck, minus engine oil.

 

[The_Roadie]

I've heard of dealers pushing their recommendations FAR FASTER than the owner's manual chart recommends. Have you memorized that chart yet?

One item to be absolutely religious about is the transfer case. No longer than 50K ever, and check the level before that. Many owners assume it's never, or 100K, and they get in deep kimchi.

 

[ChriSS K]

I've heard of dealers pushing their recommendations FAR FASTER than the owner's manual chart recommends. Have you memorized that chart yet?

One item to be absolutely religious about is the transfer case. No longer than 50K ever, and check the level before that. Many owners assume it's never, or 100K, and they get in deep kimchi.

Does the 50K rule apply even if its hardly used in 4X4?

 

[rcam81]

Yes because the parts are still rotating.

 

[The_Roadie]

Does the 50K rule apply even if its hardly used in 4X4?

An amazingly common misconception. Same thing for the front differential. Not *all* the parts are spinning, but enough do that the fluid level is critical. Excellent question!

 

[ChriSS K]

An amazingly common misconception. Same thing for the front differential. Not *all* the parts are spinning, but enough do that the fluid level is critical. Excellent question!

Thanks for clearing that up. I need to make this ride last as long as I can and if that means changing fluids I wouldn't normally than so be it. I'm use to only changing engine oil and coolant. This is my first "newer" car and I'm use to the old school mindset that you don't EVER change the trans or rear fluid.

 

[Wooluf1952]

IMO, as long as you're using Dex-cool and it still looks pinkish and clean, 5 years or 150k miles which ever comes first.
I don't think early changes are necessary.

 

[tom1999d]

My old 02 had one but my newer 07 doe snot. The spot in the casting where it would be drilled and tapped is there. Is this some kind of cost reduction!

 

[Wooluf1952]

My old 02 had one but my newer 07 doe snot. The spot in the casting where it would be drilled and tapped is there. Is this some kind of cost reduction!

Yes. The cost of the plug and machining the the hole.

 

[tom1999d]

View attachment 23096

Removing the cover requires the spare to be removed. The bolts all have loctite so be careful. Be sure you can remove the fill plug before doing anything. I use PTFE tape on the fill plug to make removal easy next time. The cover gasket is reusable but just in case I bought a spare (#12479020 from gmpartsdirect.com $12.77) The entire job took 1:45. I do miss the plug on my old 02.....

 

[playstrings]

Ok, I am lazy and not prone to create work (although thinking of some sonnax parts for my tranny) .. but I think I would drill and tap that cover- or weld a little thicker piece on if the cover is thin .....just a thought. Looks like lots of room for the plug.