Originally Posted by StevieC
Dexcool is fine now because the bugs have been worked out in the cooling system of GM vehicles. That said I wouldn't use Dexcool in any other system that didn't come with it originally but in the systems it's designed for it's fine. Neighbours wife had a Sunfire and now a Chevrolet Cruz both with Dexcool. No issues.
I think where a lot of the problems happened with the sludging issue which lead to the "Deathcool" slogan was people mixing things into Dexcool that wasn't compatible even though it said it might have been. Eg: "Universal coolants" used as top-off or for partial drain/fill's instead of Dexcool from GM.
Similar happened with Chrysler vehicles and their OAT formulations being mixed with other stuff that shouldn't have been.
I was a tech for a government fleet when this whole Dexcool thing was going on and believe me this didn't happen because of mixing of coolants (at least with us). This happened because of poor engine design. We saw it ALL OF TIME in the GM passenger cars, not so much in the trucks or even the 3.8's, but the smaller V6's...I can't remember what they were...3.4's? Yeah I believe that's what they were. Those intake gaskets were so thin from the factory, they'd just tear, then leak, then they were done. We didn't really blame the Dexcool on it, but YES the Dexcool would sludge up if the system was low and had air in it...it'd sludge up a lot. And yes the Dexcool probably did weaken the little rubber on those intakes and cause them to fail, but the gaskets, those intakes, those engines were poorly designed. The 3.8's? They would fail on the intakes because they ran the EGR tube right through the intake gasket, it'd crack or melt...then it'd fail. The trucks? The 5.3's, the 5.7's? I don't think I ever changed an intake or had a Dexcool problem. But the 3.4's in the Malibu, the Buick Regals, the Pontiac Grand Ams and Grand Prix's, the Impalas...I was replacing one a day. And it went on for years.
Now? I have not seen one single coolant issue on a GM vehicle. Other problems, yes, but not coolant related...not big known issues with leaks and poor design. That 3.4 Motor was a nightmare...stuff of legends. They'd click and clank even when they were running "good". The wrist pins in the pistons would be loud upon start up. The lifters would sometimes fail. The EGR systems would clog up. The rear spark plugs were a nightmare to replace. Misfire machines with vacuum leaks, sensor failures, EGR problems, throttle body problems...just a ratty little engine. The weird part is, you'd fix them and they'd just keep on going. I mean as poorly designed as they were, you could fix them and they'd keep on going. But lower intake design was a disaster. They used RTV at the factory to connect the intake to the opposing heads! Then they'd lay this cheap, thin gasket between the head ports and the intake, with push rods wedged right through them. It really was a mess. And they sold a ton of these cheap vehicles...and throw that engine in all of them.