Chevy Silverado and GMC Sierra Forum banner
1 - 20 of 103 Posts

· Servicemen
2021 GMC Sierra Denali CC 4WD Ultimate 6.2L
Joined
·
5,369 Posts
Every 150,000 miles or 5 years, whichever come first. Refer to Pages 10-20 and 11-6 through 11-8 of your owners manual.

PS - The build date is on the tire pressure label, drivers door, B piller. A silver label, date is in top RH corner, month and year made (MM-YY).
 

· Servicemen
2021 GMC Sierra Denali CC 4WD Ultimate 6.2L
Joined
·
5,369 Posts
Dexcool is not deep red, more a light orange/pink.
 

· Servicemen
2021 GMC Sierra Denali CC 4WD Ultimate 6.2L
Joined
·
5,369 Posts
I don't know what that could be as I never seen or heard of coolant that is deep red. Deep red is the color of automatic transmission fluid. If you have a pic of the color it will help.

Its not a rusty color is it?
 

· Servicemen
2021 GMC Sierra Denali CC 4WD Ultimate 6.2L
Joined
·
5,369 Posts
Here is what OEM Dexcool looks like. Not deep red to me but everyone's eye perceive colors differently.

 

· Registered
Joined
·
1,212 Posts
Discussion Starter · #10 ·
That may be it. Under a dark hood, it probably looks darker.

You guys take on a flush if your a newb? I've changed oil and done a ton of electrical work on cars but that's about it. I want to start doing as much as I can. Transmission filter and flush will be something I take in and differential as well but I feel I can probably do the rest.
 

· Servicemen
2021 GMC Sierra Denali CC 4WD Ultimate 6.2L
Joined
·
5,369 Posts
I never have but then again I usually trade in before 5 yrs so it not a problem
 

· Registered
Joined
·
2,304 Posts
I would not flush with chemicals, just do a couple of clean water garden hose flushes followed by a couple distilled water flushes. Each time you drain the radiator you exchange 2 gallons of water.

When I flush, I take off the upper radiator hose and the lower. Flush the radiator from the top for several minutes. Then go to the fill tank with your hose and make a small seal with your hands. With a light to medium water pressure flush out the motor for several minutes. You will see the water coming out of the upper radiator hose. It will turn clear when you get it all. You don't need a lot of pressure at the fill tank or a perfect seal with your hands. Once you start you will see what I mean.
 

· Registered
Joined
·
1,212 Posts
Discussion Starter · #13 ·
Ok, so the coolant looks like the pic above but it's a mm or 2 lower than cold full. I'm planning on either doing a flush or drain and refill. Picked up prestone full strength (2 gallons) and some flush but I'm reading that usually a drain and refill is all that is needed if the fluid that is coming out looks ok. Is that what the consensus here believes as well? I'm prepared to do either but would prefer to do the drain and refill. Is the prestone ok and is a drain and refill ok?

Thanks again!
 

· Registered
Joined
·
2,304 Posts
Yes if it looks good coming out do not use the flush. Prestone Dex is as good or better than any other. The orange stuff. It will turn pink once installed.
 

· Registered
Joined
·
2,304 Posts
Yes with just a drain and no flushing put in 50/50.
Someone else will have to chime in the trans and oil coolers.
50,000 is pretty common to do a transmission pan drop and filter change. GM says 100,000 at normal driving conditions 50,000 under heavy conditions. Most people like to change at 50,000.
 

· Registered
Joined
·
105 Posts
To the OP, I had an old "old school" radiator guy tell me long ago to ALWAYS use distilled water with antifreeze, so do whatever you can to use as much distilled water (50:50) with AF when you refill.
Buy the undiluted DexCool, it's not much more than the mixed stuff which is only half AF and half water. Distilled water is only about $1 a gallon and you'll probably only need two, maybe three if you spill a bunch.
I save my empty AF jugs and mix whatever AF I have left with distilled water, mark the jug, then any time you or anyone else in your household adds coolant or if you keep it in the truck, it's ready to use.
I did mine at 50K, didn't cost a lot, it's cheap insurance.

Also since you seem to be in the learning mode, I was also told many years ago to only use distilled water if you have to add any to a car battery, if you happen to have any that are serviceable.

GM says 97 or 100K for the tranny AND FILTER but that's the absolute MINIMUM maintenance you should do.
I did mine at 50K and even tho many guys say I wasted my money, I'll do it again at 100K. Again it's cheap insurance, tranny's ain't cheap!
There's some really good posts on here that give you step by step instructions.

You said you'd take your truck to someone to have the differential(s) done, why?
That's one of the simplest, easiest things you can do in your driveway.
You might need to drive it up on a couple wooden 4 x 4's (if you suffer from "largicus stomachus" like me) but the only special tool you'll need is a torque wrench. It's no tougher than doing an oil change.
There's probably some posts here on that too.

It's not all about doing it cheap and saving money, it's about knowing it's done right because you did it and you used good, quality parts, and that usually ends up being cheaper than taking it to someone who may be using whatever brand of parts is cheapest.
 

· Registered
Joined
·
1,212 Posts
Discussion Starter · #18 ·
So just do the transmission cooler (external that came with towing package) when the tranny is serviced? Is the tranny service done yourself or is that one for the shop.

One more question about the coolant, it's about an inch low of the cold full mark, should I too that off with 50/50 until I do the coolant which will be next weekend due to some fun wet and cold weather coming or just wait a week and do the coolant then? I bought 2 gallons on full strength so if I just do a drain and fill, I should have some to top off at the moment but wasn't sure if an inch low of coolant is to be concerned?

Thanks for the help guys! Really really appreciate it!
 
1 - 20 of 103 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top