GM "DEX" Fluids: whats the deal?

[havoc1482]

So I've always wondered whats up with DEXCOOL and DEXRON.

I've heard Dexcool is total crap, but why?

And what makes Dexron different from other AT Fluids?

I feel like I'm about to open a can of worms, but my quest for knowledge never ends lol.

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[gandhi_2006]

dex and gm had a "deal" where they recommend only this product but you can use whatever for the most part. I don't ever recommend dexcool and never put it in. It has been linked with eating gaskets in the block and destroying other parts as well. When air mixes with the hot dex it becomes acidic. You can use it but flush and clean very often. Personally I use peak performance 50/50.

[Ghost]

werent those Dexcool issues years ago and the formula now is fine?

[havoc1482]

1 hour ago, Ghost said:

werent those Dexcool issues years ago and the formula now is fine?

Thats what I heard. It ate lower intake manifold gaskets on some of the late 90s-early 2000s V6s. Dunno if it was the 3800 or the 60*V6. Or both.

 

[dreadpirateroberts]

Dexcool is like many other long-life coolants that are based on organic acid technology. The formulation is unique, but the additives can be found in many other coolants. The issue with Dexcool is that when a cooling system developed a leak, which introduced air into the system, fumes from the dexcool + oxygen + heat formed a very corrosive mixture that would attack any steel parts inside the cooling system. That is the source of the brown sludge many people complained about.

Properly maintained, a system containing dexcool will work fine for a long time.

The problem with modern GM cooling systems isn't dexcool, it is the use of plastic parts in the cooling systems. the plastic will become brittle and break over time.

The intake manifold gaskets in many GM cars were basically o-rings that were supported by a plastic body. The plastic degraded over time and cracked, allowing the o-rings to squirm around and eventually let coolant seep past them. Many newer gasket designs use metal bodies to hold the o-rings instead. Or, the intake manifolds themselves are designed with grooves to hold the o-rings, such as in LS motors.