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Hello,

I added a small amount of green antifreeze to my organization's Chevy 1500. I later noticed a sticker that stated to add only Dexcool antifreeze and that anything else could shorten the the required time between coolant changes. So, I have a few questions: 1) Will non Dexcool coolant really shorten the required time as stated or is this a product markup? 2) If it is bad to have added a different kind of antifreeze, is it as simple as just shortening the life of the coolant in the system or can the results be more dire (i.e. corrosion to the engine or radiator)? and 3) If you recommend flushing the system and putting straight Dexcool back in, can I use the flushed Dexcool/green mixture safely in other vehicles that take regular antifreeze? To clarify, I added perhaps a half gallon or less of the green into our Chevy's system. Thanks for your help,

Andrew
 

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Hello,

I added a small amount of green antifreeze to my organization's Chevy 1500. I later noticed a sticker that stated to add only Dexcool antifreeze and that anything else could shorten the the required time between coolant changes. So, I have a few questions: 1) Will non Dexcool coolant really shorten the required time as stated or is this a product markup? 2) If it is bad to have added a different kind of antifreeze, is it as simple as just shortening the life of the coolant in the system or can the results be more dire (i.e. corrosion to the engine or radiator)? and 3) If you recommend flushing the system and putting straight Dexcool back in, can I use the flushed Dexcool/green mixture safely in other vehicles that take regular antifreeze? To clarify, I added perhaps a half gallon or less of the green into our Chevy's system. Thanks for your help,

Andrew
Don't do it!!!

My buddy owns a repair shop and says that Dexcool mixed with green antifreeze can cause a brown sludge to form in your radiator. This is the whole reason that Dexcool is colored and orange/red and regular antifreeze is colored green.
 

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I don't know what year your truck is, but you should go and have the system flushed and refill with DexCool. DexCool is a required coolant in most all GM vehicles after 1995, if I'm not wrong. But DexCool chemistry behind DexCool is such that it will not harm the environment if there is an accident or leakage. The formula is such that if it is exposed to air, it neutralize itself. With ethylene Glycol or Green coolant, if spilled it is poison to any and all animals who might ingest it. The internet is full of horror stories of and about DexCool, but the problems with vehicles that had problems were due to an idiots design of head and intake manifold gaskets, not the coolant. But once more, The Green coolant will cause a problem with the DexCool as the two are totally different chemicals. You made a simple mistake, protect your engine and go ahead and have it flushed out and refill with DexCool, FWIW, DexCool has a useful life of 5 years, I am going to have my other car which came from Bowling Green with DexCool and I change it every 5 years like clockwork.:great:
 

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Like stchman said, DO NOT mix Dexcool with other antifreezes!!

I had a buddy do that to his Silverado and it corroded through his radiator. Dexcool only!! If you want to change to non-Dexcool antifreeze, you'll have to do a complete/thorough flush.
 
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It states on every bottle of Dex-cool that if it is mixed with green antifreeze it dramatically shortens the life of the coolant. Also in some cases cheap green coolant can turn Dex cool into acid that can damage the radiator and engine.
 
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Ok, so someone put the green stuff in my truck before I bought it, I flushed it out with water and RR the heater hoses which were plugged up with "mud". The water flush didn't do much, what can I used to get the brown coating off of the inside of my engine, radiator, and assuming the heater core ? Replacing those parts IS an option I have thought about if all else fails
 

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Google rad flush, the shops use an acid mix to clean out the sludge.
 

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I gotta go with Ray on this one. Auto cooling professionals have both the knowledge and equipment to do a complete forward and reverse flush on your engine and heater. I am lucky as I have a coolant A/C shop only about 10 miles from my home. I wanted to get a new heater core in my 1990 Silverado as it's a job that would take me a day and a half. George did the complete job in 2.5 hours, and he cleaned out the heater box, flushed the system drained it and refilled it with green anti freeze ( That's what came with when it was new in 1990) It cost about $300.00 but it was well worth it, comes with a warranty but more important, I have a "brick & mortar" business to go to if there ever a problem.
 

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Googled the rad flush and presently have a gallon of white vinegar in after draining out the Dexcool that was in there and did a water flush 3 times. As recommended I'll leave it in for a day or so (I see it's already working), flush it out and repeat if needed (likely will) getting a new cap and t-stat tonight when I go to town. When it gets cleaned out to my satisfaction I have Zerex ready to go in, if not, a new radiator will go in
 

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I think you did the right thing, Dexcool and its compatibility with other antifreeze is a really big issue for a number of reasons. Couple of thoughts-

Use what the manufacturer specifies most of the time. One exception is for GM V6 and V8 engines from 1996-2005 because the Dexcool GM insisted on liquifies the intake manifold gaskets. GM settled a class action suit about that a few years ago but the window for claims is closed. I think our trucks are better off if you flushed the Dexcool and used the Prestone. Even the remaining Dexcool will attack the intake manifold gaskets unless they have been replaced since 2005. Ours is a case where using the *right* coolant will cause damage.

Prestone Long Life (the straw colored "universal" coolant) is compatible with Dexcool. Early Dexcool formulations had stop-leak pellets that had a lot to do with the notorious Dexcool sludge, but there were plenty of people who blamed the sludge on all sorts of things, including mixing with other coolants.
 

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Likely going to have to get a new radiator, this one has passages plugged down as far as I can see. Driver side tank it hot, passenger side you can rest your hand on it (a lot cooler). T-stat was pretty clean though, I'll finish the vinegar flush in it now but passages are still plugged. New rad with Zerex fill will do it (Zerex is the recommended coolant for my Benz so . . . . . )
 
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