Exact correct coolant for 99 Yukon

[eliminatethebug]

Hi, 99 Yukon here, 5.7L V8 gas. What is the correct coolant for a flush? I have used a little Prestone all vehicles stuff to top up in the past but I want to do a full drain & fill (disconnect lower rad hose), flush the heater core (low pressure garden hose style) and put in exactly the right stuff.

Probably will use Prestone again, it's easy to find. But which spec? I hear about Dexcool and stuff and don't want to make a mistake. I could also use all the All Makes version too??

 

[bsamole]

I have been using Dexcool in my '99 Tahoe since I bought it new (23 years ago). I have had no issues with Dexcool however there are others who don't like Dexcool. Be sure to use the GM Cooling System Seal Tablet part number 12378255 per GM instructions.

 

[YukonGTmaster]

Hi, 99 Yukon here, 5.7L V8 gas. What is the correct coolant for a flush? I have used a little Prestone all vehicles stuff to top up in the past but I want to do a full drain & fill (disconnect lower rad hose), flush the heater core (low pressure garden hose style) and put in exactly the right stuff.

Probably will use Prestone again, it's easy to find. But which spec? I hear about Dexcool and stuff and don't want to make a mistake. I could also use all the All Makes version too??

Is the coolant in the reservoir right now, Green or Orange?

 

[Doubeleive]

the exact correct coolant to use is the one noted in the owners manual
that being said if you change it from whatever is in there now be sure it is all flushed out first

 

[gooffeyguy]

Just pee in it, lol.

I'm not sure when GM switched from green to orange antifreeze, but my 2001 5.3l takes orange as well as my 2012 6.2l.

Now the 5.7l (350 zz4 crate engine with aluminum heads) in the hotrod takes green.

Years ago, green antifreeze had a problem with aluminum, but that's not a problem anymore

 

[YukonGTmaster]

My 97 GT was equipped from factory with Dexcool coolant (Orange). Once the warranty was up, I opted to switch to Prestone (Green) because of cost and availability. As I look back, it was not long after switching I ended up with a leaking heater core. I replaced 2 radiators because of leaking plastic end caps. I have also replace 2 sets of lower intake manifold gaskets due to leaks. If I could do it all over, I would have stayed with original Dexcool, and took my chances. The vehicle to this day is still my original owner daily driver. 430k Kms.

 

[YukonGTmaster]

I have been using Dexcool in my '99 Tahoe since I bought it new (23 years ago). I have had no issues with Dexcool however there are others who don't like Dexcool. Be sure to use the GM Cooling System Seal Tablet part number 12378255 per GM instructions.

I had never heard of these tablets before. Thanks for the tip!

 

[Eman85]

If you truly want to drain the coolant you need to remove the plugs in the block. It's a messy job but it will get all of the coolant out and there is a lot in the block that doesn't come out draining the radiator and removing the lower hose. There is a plug on both sides of the block, the knock sensor is the plug on the passenger side. I've refilled with Dex-Cool or Universal antifreeze with no problems as long as there aren't any leaks.

 

[eliminatethebug]

Thanks. I will use Dexcool. The overflow bottle was almost empty so I'm not sure on what has been used in the past. The vehicle has 265,000 km on it so I'm just trying to maintain it so it can last. I don't think I will do a "full" system drain with the block plugs, I will just do as much as possible by removing lower rad hose, flush heater core, etc.

 

[willxfs]

Your 1999 rig came with the Dexcool (orange coolant). No telling what's in there now. Hopefully it is still Dexcool and hopefully it has been flushed in the past. As someone stated earlier, take note of what comes out when you drain it. Going back with Dexcool is a great idea as long as what comes out when you drain it is dexcool (orange). It is a very bad idea to mix the coolant types especially when you are not completely draining the engine block. Good luck!