Is Dexcool Really That Bad?

[garageman402]

My 2000 Montana's transmission failed, so we rebuilt it, & while the engine was out, we replaced everything likely to have issues. One of those issues is the infamous 3.4 intake manifold gasket which is prone to leaking coolant into the crankcase. The gaskets were soft & spongy at the coolant passage, getting ready to leak. These gaskets had been replaced 3.75 years & 30,000 miles ago. Used nothing but the factory recommended Dexcool 60/40 ratio.

I went to buy coolant, now everything on the shelf is "long life, use with any color coolant". I wanted the old style green coolant, but got the Prestone any color coolant which happens to be a green-yellowish color. Good thing, because there was Dexcool left in the engine, we only emptied the radiator (which we replaced) & rear heater core.

I watched the video by Flat Rate Master saying Dexcool is not bad, but GM put it in cars that had old style gaskets, & the acid in dexcool ate them up. Is the acid what's softening up my intake gaskets? These gaskets are supposedly the updated steel backed version, but they were still soft. I also read on here that Dexcool was reformulated a few years back, did that solve the issues? Flat Rate says the acid in Dexcool is what keeps the cooling system clean, & Dexcool does not mix well with air. My expansion reservoir is open to the atmosphere, so it's getting air.

Any thoughts? I'll post a link to the video mentioned.

 

[Brian123]

Flush and use the All Makes and Models Coolant or G-05

 

[slacktide_bitog]

Peak 10x is good stuff

 

[tmorris1]

No. I had a 1998 Montana and went through lower intake gaskets like candy until the head gasket went and I replaced everything with FelPro problem solver gaskets. Never had a problem and I junked it at 265k miles because it was rusted out so bad. Engine and trans still ran great. I got 24-25mpg as I drove it to the salvage yard.

Ford used it in the F-150s for quite a few years and I never had a problem with it there either.

 

[oil pan 4]

Yes.

 

[Trav]

It is not bad unless you use it on engines with wet intake manifolds. I have a couple of cars that use it and both have dry intakes, no issues and both are over 15 years old.

 

[JavierH19]

It earned the name dexkill for a reason. I always used the prestone stuff anyway. But now it's a non issue.

 

[JHZR2]

My 98 S-10 ZR2 that I’ve owned since new has run dexcool the whole time. I did replace the LIM gasket when UOA showed a few ppm of Na and K. No issues ever, entire system original.

 

[bullwinkle]

It’s only DeathCool on engines with wet nylon intake gaskets-GM smartened up on the LS & Ecotec engines & the issues disappeared. Then Ford decided they had to use it & plug up some heater cores (Specialty Orange)…

 

[64bawagon]

No.

 

[johnnydc]

I have 2 Fords that use Motorcraft orange Same as Dexcool. I haven't had any problems. Must be a GM thing. LOL

 

[zzyzzx]

Is Dexcool Really That Bad?​

No.

 

[thastinger]

I have 2 Fords that use Motorcraft orange Same as Dexcool. I haven't had any problems. Must be a GM thing. LOL

I had 2 of those as well but switched them to Yellow.

 

[64bawagon]

Like so many other GM issues, once the initial engineering mistakes are corrected the item works pretty well.

Look at Merchant automotive here in MI. He has created a thriving business based on common sense fixes for GM's engineering blunders.

 

[Snagglefoot]

I’ve been using nothing but Dexcool on 2008 Suburban for 15 years now. Original radiator, heater core and water pump. The Dexcool stories date back to 30 years ago.

 

[JohnnyG]

Dexcool wasn't the issue. It was one of the first Long Life coolants produced to handle the mixed metal and aluminum block engines. The biggest problem was people saw 5 years 100,000 miles life, and totally forgot about the 5 year part.

 

[Snagglefoot]

Here are the safety sheets for Prestone 10 year and Prestone Dexcool. Both use 2EHA along with there base ethylene glycol. The sheet for the Dexcool is pre-mixed, so the ethylene glycol number is much less because it’s diluted with water. The two are completely compatible.

One can of worms is that the premixed Prestone Dexcool you buy in Texas probably has less ethylene glycol than the Prestone Dexcool you buy in Canada. The safety sheet says the ethylene glycol concentration can vary between 30 and 60%. The 60% is pretty standard in Canada. I avoid the issue and purchase concentrate and add water myself.

Here are the safety sheets.

 

[garageman402]

Thanks for all the input! The issue I am having is with the LIM gaskets on the GM 3.4L As I mentioned in my original post, we had the engine out & replaced stuff just to replace it. The water jacket part of that gasket was soft & squishy, ready to fail. This after only 30,000 miles. Is there a direct relationship with the dexcool usage & this gasket failing? Always have used quality parts. The gasket that was in was the new improved GM item. I think we used FelPro this time, hope it lasts. I'm switching to the OG green Zerex, but still have to flush all the old crap out. Never had an issue with sludge, just the gasket failing. You can see weeping from that gasket if you can get a good view of it.

Edit: The Dexcool I was using was Havoline (the brand actually mentioned in the owners manual), I bought a 6 gallon case from Zorro a few years (5) back, & they are apparently famous for selling old stuff. Is it possible I got a batch of the old formula? It was not able to be shipped to CA, not sure why, but I think it didn't have the bittering agent that is now required.

 

[garageman402]

Well, as soon as I posted that, my Zerex Original Green arrived. I ordered from Amazon but it was drop shipped from Zoro!!

Does anyone know how to decipher the date code? They're all the same except some were from 08:34.

Would this be the 141st day of 2023 (05/21/23)?

This was on the bottom, mostly the same on all but some variances, could it be when the bottle was produced? The 13 was consistent tho, lol

 

[dogememe]

Dexcool is fine. It is the only thing I can use in my Volt in all three cooling systems. Instead of paying big money to the dealer to have it changed I bought a couple gallons of coolant from the dealer for $19 each (after I made them adjust the price because they tried to charge me $30 each even though their website said it was $19) and am using a turkey baster like thing to change it a little bit at a time through the three coolant reservoirs. I know I won't get it all that way, but it's better than not doing it at all. I'm assuming the coolant in there is original and it looks perfect, but at almost 10 years old it looks just the same as the new coolant going back in.