Im in the livery business...used to own a Suburban...know a lot of people with these vehicles. The best thing you can do is get the "Dexcool" coolant flushed and replaced with Peak Global Lifetime. Pepboys seems best equipped around here to perform these fluid flushes.
Lets say you keep cruising with Dexcool mysterious problems will happen like a leak in the radiator...a leak in the coolant reservoir...etc...
GM has been having problems with Dexcool since they started using it in 1996.
https://www.consumeraffairs.com/news04/2006/08/gm_dexcool.html
Dexcool contains an aggressive plasticizer chemical. Peak Global Lifetime is the same coolant minus that chemical.
Have the "Dexcool" coolant flushed out of your GM vehicle...
- Thread starter Navi
- Start date
Have a 2003 suburban with 245,000K on it. Coolant has been changed twice in that time. Replaced with Dexcool. One water pump replaced because it started weeping. Still on original radiator. If you realized that it is not a lifetime coolant and change it when recommend it will be fine. Just my experience. I know some gm models had intake gasket issues... when combined with Dexcool turned to mud like substance.
Many GM cars have been running dexcool for over 20 years with no issues whatsoever. Some engines had LIM gasket trouble but that was eventually resolved with aluminum frame gaskets, engines with dry intakes didn't have any such problems.
I have a few older Saab that used dexcool from day one and are perfectly clean inside the cooling passages and radiators, no bad gaskets or seals on these almost 20 year old cars, I cant see how it the "best thing" to do is change it for something else at this point.
On some engines I agree especially if it uses a wet intake or those known to have gasket issues with 2-EHA for those I use JD Cool Guard II.
Back in '96, GM made the "mistake" of calling Dexcool a "lifetime" coolant. By the early 2000s, manifold gasket failures on the 3.1L/3.4L as well as 4.3L, 5.0L and 5.7L using plastic carrier gaskets with moulded silicone was common. The root cause was air in the system, which caused acid to form when mixed with the coolant and attacked plastic carrier gaskets. The plastic would soften, swell and eventually leak. Newer gasket material, primarily HNBR with aluminum frames addressed the problem, but until that point both GM and some aftermarket manufacturers were paying for warranty claims.
I, personally, have never had a problem with Dexcool. The LM7 5.3L I had on an old Avalanche didn't cause me any grief, nether did the LL8 4.2L in my Envoy, both of which have been running Dexcool since they left the factory. Whenever a cooling system repair was performed, e.g. thermostat or water pump, the system was thoroughly flushed and back flushed and refilled with premixed Dexcool. I no longer have the Avalanche, but I personally know the person who now has it with 293,000 miles now and he's got no issues with it either. I flushed out the factory coolant on the Envoy when I replaced the factory thermostat at 56,000 miles and again when I replaced the water pump at 115,000 miles. The system is still clean all round with zero issues at 135,000 miles, which is stil less than half that of the Avalanche.
The Dex-Cool problem has not existed in decades. I have a 1999 GMC Sierra that has had it as the coolant all of it's life with no problems. I have a friend with a 2006 Silverado with well over 300,000 miles that has used nothing but Dex-Cool. He had to replace a water pump and the radiator but both went out at over 300,000 miles so you can't blame the coolant on that.
I think the Dexcool problem has been solved . But if you wish to change , go right ahead .
Originally Posted by Navi
Im in the livery business...used to own a Suburban...know a lot of people with these vehicles. The best thing you can do is get the "Dexcool" coolant flushed and replaced with Peak Global Lifetime. Pepboys seems best equipped around here to perform these fluid flushes.
Lets say you keep cruising with Dexcool mysterious problems will happen like a leak in the radiator...a leak in the coolant reservoir...etc...
GM has been having problems with Dexcool since they started using it in 1996.
https://www.consumeraffairs.com/news04/2006/08/gm_dexcool.html
Dexcool contains an aggressive plasticizer chemical. Peak Global Lifetime is the same coolant minus that chemical.
JHZR2
Staff member
My 1998 S-10 still has all original cooling system components, less the LIM gasket and the radiator cap.
Issue if maintained? Not so much. Certainly not the boogeyman some make it out to be.
Coolant always comes out beautifully clear.
The others have handled the response well. I've had Dexcool in my Suburban's rad for 12 years, changing every 5 years. 200,000 miles on the original rad, heater core, and water pump. 
Last edited:
As "hands on and on top of things" people say they are, incorrect coolant is likely added to vehicles often....when you're not looking.
This can cause sludge.
An airtight system is a must, I've read.
I rinsed "Christmas Coolant" (red and green) from our 2005 Saab and restored with Dex-Cool & distilled.
We had crystal clear "Dex orange-red" through our ownership.
For the yokels who learned to say, "Death-Cool", there's no going back.
That's the trouble with headlines and bumper stickers.
Shame on the automotive industry for using the term "lifetime".
Dexcool has been super reliable for over 15 years now.
[censored], I know some people that have NEVER changed their coolant in suburban sand Tahoe's. Never. Going on almost 300,000 miles with one guy...opened the coolant tank and it smelt like fish. Said, you better change that. But he didn't.
I have stayed with Dexcool in my Sierra and have no intentions of changing it out for another coolant. Dexcool has been changed twice so far. Original rad, water pump, heater core.
ls1mike
$50 Site Donor 2022
I can't believe this still comes up. Dexcool hasn't been a problem in 15 years.
Everything I own runs it. Never had a problem with in the LS series of engines.
The problem was when it ran low and the intake gasket failed because it broke down. Then it would sludge up.
Problem was fixed in 04 on the 3800 engines.
Even the comments on airtight are are probably a red herring. AFAIK, most or all cooling systems built in the last 20 years are air tight, using a sealed cap and pressurized coolant jug. Yes, my grandpa's 73 Ford was not air tight. 
Dexcool was good for 5 years 100,000 miles at first and then 150,000 miles. At six years I took my 2004 Silverado for a flush and was advised a flush was not necessary, drain the radiator and replace with new Dexcool. Another independent wrench told me he didn't like Dexcool because it turns to jelly but admitted that was because owners never changed it. I had the Silverado 14 years and currently have a 2008 Saturn Vue and don't have any problems with Dexcool. I also have an old Pontiac with a Griffin aluminum radiator and they recommend Dexcool. Every few years, drain what you can and replace with new. I buy a gallon of distilled water for less than $1 with every gallon of Dexcool and poor them both in a sprinkling can for a 50/50 mix.
Biggest thing is-don't let quick change oil places or other idiots near your cooling system! We've had a couple of Transits, using Ford's very Dex-like Specialty Orange, sludge up heater cores because VIOC and other idiots dumped "universal" Maxlife coolant into them. If you drain the radiator every couple of years (decades?) and refill with 50/50 Dex and distilled water, the Dex problems go away (on newer non-nylon, non-wet LIM gasket engines).
I had a 99 S10 with the 4.3 with Dexcool and did not know any better at the time and added the wrong coolant doing some maintenance. It was OK for quite a while until one cold morning I had no heat and found out the heater core was clogged. I flushed out the system and replaced with new Dexcool and never had another problem. I sold the truck with over 200K on it and it still ran just fine. I freely admit the trouble with the Dexcool was my own ignorance to "new" coolant instead of standard 'ol green coolant I had always worked with. I am more than happy to admit it and tell others to try and avoid any trouble.
Yes some engines had tons of lower intake gasket failures but that was a combination of poor quality gaskets and people not changing the coolant often enough or mixing it with incorrect coolant.
Personally I have nothing against dexcool. It works fine. If it was so terrible GM wouldn't have kept using it for 20 years and now other manufacturers are using it too.
OP, I wouldn't be in a hurry to change it out on a new vehicle but after a couple of years I would clean the system and replace it with something else. I changed all of my vehicles to G-05 years ago and have never found a reason to switch back or use to anything else. I suffered from the intake manifold and then later a head gasket failure on a GM 3.4L engine that came with the Dexcool. I had also changed an older Toyota to this new at the time and "better" (sic) coolant in the late 1990's and then experienced a heater core leak. I knew others with similar problems but all of this was over a decade ago.
