Coolant help
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Joined: 04-01-06
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From: Atlantic Canada
GM Dexcool. It's orange.
Do not mix anything else with it and disregard any silly Dexcool horror stories related to 15-20 years ago. Here's some info on dexcool misinformation.
"There is probably more misinformation, conjecture, and outright BS on the internet about DexCool coolant than any other single automotive product ever made.
It is compatible with regular coolant, you just lose all of the long life properties if you mix them. It does not "react" and sludge does not come from mixing them. - sludge, we will get into that.
It does not cause leaks it does not eat gaskets any more than green (slilicated coolant) does. It does tend to clean off silicate deposits that plug leaks in older systems that have had silicated coolant in them. And that brings up another reason to use DexCool, - if anyone here has ever actually taken apart an engine that had silicated coolant in it for years you will find a white flaky coating on the inside of the cooling system. That coating is silicate that is there to protect the parts from electrolytic contact with the coolant. This barrier is also a barrier to heat rejection - so why would you want a coating of silcate between the heat and the water on your high performance car? You wouldn't. DexCool actually treats the aluminum in the engine through a process similar to the process that is used in bluing a gun barrel to help prevent corrosion of the metal. It does not leave a thermal barrier on the surface it bonds to the first couple of microns of metal in the aluminum components to protect them from corrosion. In addition, the silicate is a hard mineral that is loose and floating around in the cooling system (those flakes break off and circulate around randomly). The flakes can get into the seals in the water pump and cause them to wear out and fail - this was one of the prime reasons for GM going to DexCool in the first place.
It can be more agressive at forming sludge in the closed (pressurized) part of the cooling system if air gets trapped or is allowed into the pressurized side of the cooling system. This issue is easily resolved by fixing the source of the unwanted air. You don't want air in there anyway so getting it out is a good thing. The most common part that causes air to get trapped in the system is a bad radiator cap. GM got a bazillion caps from a company called Stant that leak air and that hasn't helped the situation. Too bad, because Stant had an excellent reputation right up to that point.
Deposits on the overflow bottle (and dipstick on F-Cars) are common with all kinds of coolants. There is commonly some machining oil and/or sealing additive in the coolant on new cars and eventually that stuff migrates to the overflow bottle leaving a scummy line on the inside of the bottle and on the stick. It is not harmful, it does nothing to the effectiveness of the cooling system.
As far as compatibility, there is some back-and-forth on that. GM does not approve of the use of DexCool in any vehicle that uses a copper/brass radiator or a copper/brass heater core. GM's concern is with the solder in those components and a process called "solder bloom" where chemicals leach out and deposit themselves on the solder joints of the copper/brass components.
Havoline, the maker of the orginal DexCool coolant says that it is fine with the solder in these components. And the only GM car made in the last 10 years with a copper/brass radiator was the pre 1995 Chevrolet Cavalier and Pontiac Sunbird. None of us own those and if we do we probably aren't going to put new coolant in them unless a hose pops."
One former GM tech that I work with says the LIM leaks started when GM switched to using plastic gaskets instead of paper. The paper gaskets cause pitting on the surfaces which they were mated to so that's why GM changed them."
Do not mix anything else with it and disregard any silly Dexcool horror stories related to 15-20 years ago. Here's some info on dexcool misinformation.
"There is probably more misinformation, conjecture, and outright BS on the internet about DexCool coolant than any other single automotive product ever made.
It is compatible with regular coolant, you just lose all of the long life properties if you mix them. It does not "react" and sludge does not come from mixing them. - sludge, we will get into that.
It does not cause leaks it does not eat gaskets any more than green (slilicated coolant) does. It does tend to clean off silicate deposits that plug leaks in older systems that have had silicated coolant in them. And that brings up another reason to use DexCool, - if anyone here has ever actually taken apart an engine that had silicated coolant in it for years you will find a white flaky coating on the inside of the cooling system. That coating is silicate that is there to protect the parts from electrolytic contact with the coolant. This barrier is also a barrier to heat rejection - so why would you want a coating of silcate between the heat and the water on your high performance car? You wouldn't. DexCool actually treats the aluminum in the engine through a process similar to the process that is used in bluing a gun barrel to help prevent corrosion of the metal. It does not leave a thermal barrier on the surface it bonds to the first couple of microns of metal in the aluminum components to protect them from corrosion. In addition, the silicate is a hard mineral that is loose and floating around in the cooling system (those flakes break off and circulate around randomly). The flakes can get into the seals in the water pump and cause them to wear out and fail - this was one of the prime reasons for GM going to DexCool in the first place.
It can be more agressive at forming sludge in the closed (pressurized) part of the cooling system if air gets trapped or is allowed into the pressurized side of the cooling system. This issue is easily resolved by fixing the source of the unwanted air. You don't want air in there anyway so getting it out is a good thing. The most common part that causes air to get trapped in the system is a bad radiator cap. GM got a bazillion caps from a company called Stant that leak air and that hasn't helped the situation. Too bad, because Stant had an excellent reputation right up to that point.
Deposits on the overflow bottle (and dipstick on F-Cars) are common with all kinds of coolants. There is commonly some machining oil and/or sealing additive in the coolant on new cars and eventually that stuff migrates to the overflow bottle leaving a scummy line on the inside of the bottle and on the stick. It is not harmful, it does nothing to the effectiveness of the cooling system.
As far as compatibility, there is some back-and-forth on that. GM does not approve of the use of DexCool in any vehicle that uses a copper/brass radiator or a copper/brass heater core. GM's concern is with the solder in those components and a process called "solder bloom" where chemicals leach out and deposit themselves on the solder joints of the copper/brass components.
Havoline, the maker of the orginal DexCool coolant says that it is fine with the solder in these components. And the only GM car made in the last 10 years with a copper/brass radiator was the pre 1995 Chevrolet Cavalier and Pontiac Sunbird. None of us own those and if we do we probably aren't going to put new coolant in them unless a hose pops."
One former GM tech that I work with says the LIM leaks started when GM switched to using plastic gaskets instead of paper. The paper gaskets cause pitting on the surfaces which they were mated to so that's why GM changed them."
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