I used it for over 100,000 mi. not one problem 
DexCool Issues
Thread Starter
Team Owner
Joined: Sep 2005
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From: Big Bend Country, TX
St. Jude Donor '06-'07-'08-'09-'10-'11-'12-'13-'14-'15- '16-'17-‘18-‘19-'20-'21
NCM Lifetime Member
Thread Starter
Team Owner
Joined: Sep 2005
Posts: 29,113
Likes: 2,194
From: Big Bend Country, TX
St. Jude Donor '06-'07-'08-'09-'10-'11-'12-'13-'14-'15- '16-'17-‘18-‘19-'20-'21
NCM Lifetime Member
Thank you. I have to agree with you. I just thought it safer to ask.
Safety Car
Joined: May 2006
Posts: 4,289
Likes: 129
From: Providence Forge, VA
St. Jude Donor '08-'09-'10-'11-'12
The reported problem occurs when coolant types are mixed without a serious flush as I recall.
Pro
Joined: Mar 2005
Posts: 713
Likes: 62
From: Melbourne Fl.
I have 5 GM vehicles in my household that use Dexcool and only had a problem with one of them, a 96 Astro Van. The heater core, and radiator were clogged with Dexcool sludge. However, there was a leak in the heater hoses that allowed air to get into the system. I kept it full as best I could until I was able to replace the hoses but the damage was done. I had to flush the heater core and hoses, and replace the radiator.
I've always done my own coolant maintainance since the van was new and always use distilled water to flush and fill.
Warren
06 DSOM Vert,Z51,M6
Team Owner
Joined: Jun 2005
Posts: 46,295
Likes: 2,596
From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
Don't know if it's a perceived or real problem, but even in the later year C4s, there were engines with issues from Dex. Several owners commented, similar to here: if you let the rad system coolant get either "old" or let it go low (for whatever reason, since the system isn't supposed to have a leak that would cause it to go low), then there may be sludge build up.
It can build up on the cap, in the plastic overflow tank( in C4s), etc. Then, it requires a thorough cleaning out.
I've heard of no issues in C6s. Again, maintenance, lack of overheating the system and watching the level seem to be the things to do. That said, I don't know why one would swap out the Dex for something else unless they had a problem with it.
It can build up on the cap, in the plastic overflow tank( in C4s), etc. Then, it requires a thorough cleaning out.
I've heard of no issues in C6s. Again, maintenance, lack of overheating the system and watching the level seem to be the things to do. That said, I don't know why one would swap out the Dex for something else unless they had a problem with it.
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Burning Brakes
Joined: Jul 2006
Posts: 849
Likes: 2
From: Southern Florida
The problem with it is that it eats through the intake manifold gaskets on some GM engines. (to the tune of about every 40k miles and the repair isn't exactly cheap.....~$700 if done by a mechanic)
From what I have read, this issue is concentrated mostly on GM V-6 engines though also effected various GM V-8's as well. The intake manifold gasket went back on my old LT-1 at about 45k miles (though it was fixed under warranty)
From what I have read, this issue is concentrated mostly on GM V-6 engines though also effected various GM V-8's as well. The intake manifold gasket went back on my old LT-1 at about 45k miles (though it was fixed under warranty)
Le Mans Master
Joined: Dec 2006
Posts: 7,251
Likes: 16
From: Phoenix Arizona
been like that for over 40 years! :O
Drifting
Joined: Feb 2007
Posts: 1,537
Likes: 1
From: Southlake Texas
Some cars had considerable trouble that was traced to air leaks - mostly caused by the pressure cap.
Joint GM and Texaco Report:
"GM’s Jay Dankovich and Equilon Enterprises’ (Texaco) Stede Granger directed a 2-year study of thousands of DEX-COOL cooled vehicles. Armed with the results, they really didn’t have anything bad to say about the coolant. In fact, they strongly defended the product’s reputation. What they revealed to the audience is that specific models of GM vehicles have specific cooling system contamination problems. And essentially, that DEX-COOL is not the culprit!
What was said at the presentation? Besides the video, Jay and Stede included their personal observations about the study. At the end, they fielded several questions from the audience. Here’s a recap of their entire presentation:
1. Keep the cooling system filled. In fact, fill the reservoir bottle to “Hot” level when the system is cold. Problems arise when a system’s coolant level is not maintained. (Fleet vehicles receiving regular maintenance, and with reservoirs kept slightly above normal, do not show signs of contamination. This even applies to the specific “problem” vehicles.)
2. The coolant problems found in this survey were caused by system contamination, and not due to the breakdown of DEX-COOL.
3. Check and keep the pressure cap clean and functioning. A contaminated and/or malfunctioning cap causes low coolant levels, which in turn causes overheating and a greater loss of coolant: the notorious vicious cycle. No matter what the vehicle, if the cooling system acts suspiciously, test the pressure cap.
4. On the ST vehicle models mentioned in the GM DEX-COOL video, you “must” replace all suspect radiator caps, especially those with a Drop-Center design, with a Stant Model 10230 or 11230 (Spring-Center type). (Just do it.)
5. Make sure that the coolant is at a 50-50 mix. Often, the flush water was not being removed from the engine block. Consequently, when a 50-50 mix is added to the system the resultant mixture could approach 30-70. Like any fluid that has been diluted beyond its recommended levels, the lowered level of inhibitors will not be able to protect the coolant system effectively. Low levels of inhibitors can cause pitting on aluminum surfaces and general corrosion of cooling system metals.
6. A safe method of achieving a true 50-50 mix is to first determine the actual capacity of the system (use the owner’s manual). Then add 50% of “that” amount of undiluted DEX-COOL (or any coolant), and top it off with water.
7. Mixing a “green” coolant with DEX-COOL reduces the batch’s change interval to 2 years or 30,000 miles, but will otherwise cause no damage to the engine. In order to change back to DEX-COOL however, the cooling system must first be thoroughly drained and flushed.
8. Bacteria cannot live in a hot, Ethylene Glycol environment and is therefore not a threat to DEX-COOL.
9. While there have been intake gasket failures on CK Series, V8 powered vehicles for various reasons, DEX-COOL has never been found as a cause.
10. Use a refractometer to check the condition of DEX-COOL. Its inhibitor package is strong enough that if the batch still provides proper freeze protection, it is probably still providing proper corrosion protection as well.
11. DEX-COOL can handle the minerals in hard water better than silicated conventional chemistry coolants. Drinkable water is suitable for top off.
12. In ST Blazer applications where the radiator cap is mounted at an angle to the ground, the vehicle is more susceptible to radiator cap contamination and its related problems. The Stant 10230 is a wise choice for these vehicles."
Joint GM and Texaco Report:
"GM’s Jay Dankovich and Equilon Enterprises’ (Texaco) Stede Granger directed a 2-year study of thousands of DEX-COOL cooled vehicles. Armed with the results, they really didn’t have anything bad to say about the coolant. In fact, they strongly defended the product’s reputation. What they revealed to the audience is that specific models of GM vehicles have specific cooling system contamination problems. And essentially, that DEX-COOL is not the culprit!
What was said at the presentation? Besides the video, Jay and Stede included their personal observations about the study. At the end, they fielded several questions from the audience. Here’s a recap of their entire presentation:
1. Keep the cooling system filled. In fact, fill the reservoir bottle to “Hot” level when the system is cold. Problems arise when a system’s coolant level is not maintained. (Fleet vehicles receiving regular maintenance, and with reservoirs kept slightly above normal, do not show signs of contamination. This even applies to the specific “problem” vehicles.)
2. The coolant problems found in this survey were caused by system contamination, and not due to the breakdown of DEX-COOL.
3. Check and keep the pressure cap clean and functioning. A contaminated and/or malfunctioning cap causes low coolant levels, which in turn causes overheating and a greater loss of coolant: the notorious vicious cycle. No matter what the vehicle, if the cooling system acts suspiciously, test the pressure cap.
4. On the ST vehicle models mentioned in the GM DEX-COOL video, you “must” replace all suspect radiator caps, especially those with a Drop-Center design, with a Stant Model 10230 or 11230 (Spring-Center type). (Just do it.)
5. Make sure that the coolant is at a 50-50 mix. Often, the flush water was not being removed from the engine block. Consequently, when a 50-50 mix is added to the system the resultant mixture could approach 30-70. Like any fluid that has been diluted beyond its recommended levels, the lowered level of inhibitors will not be able to protect the coolant system effectively. Low levels of inhibitors can cause pitting on aluminum surfaces and general corrosion of cooling system metals.
6. A safe method of achieving a true 50-50 mix is to first determine the actual capacity of the system (use the owner’s manual). Then add 50% of “that” amount of undiluted DEX-COOL (or any coolant), and top it off with water.
7. Mixing a “green” coolant with DEX-COOL reduces the batch’s change interval to 2 years or 30,000 miles, but will otherwise cause no damage to the engine. In order to change back to DEX-COOL however, the cooling system must first be thoroughly drained and flushed.
8. Bacteria cannot live in a hot, Ethylene Glycol environment and is therefore not a threat to DEX-COOL.
9. While there have been intake gasket failures on CK Series, V8 powered vehicles for various reasons, DEX-COOL has never been found as a cause.
10. Use a refractometer to check the condition of DEX-COOL. Its inhibitor package is strong enough that if the batch still provides proper freeze protection, it is probably still providing proper corrosion protection as well.
11. DEX-COOL can handle the minerals in hard water better than silicated conventional chemistry coolants. Drinkable water is suitable for top off.
12. In ST Blazer applications where the radiator cap is mounted at an angle to the ground, the vehicle is more susceptible to radiator cap contamination and its related problems. The Stant 10230 is a wise choice for these vehicles."
Le Mans Master
Joined: Dec 2006
Posts: 7,251
Likes: 16
From: Phoenix Arizona
Some cars had considerable trouble that was traced to air leaks - mostly caused by the pressure cap.
Joint GM and Texaco Report:
"GM’s Jay Dankovich and Equilon Enterprises’ (Texaco) Stede Granger directed a 2-year study of thousands of DEX-COOL cooled vehicles. Armed with the results, they really didn’t have anything bad to say about the coolant. In fact, they strongly defended the product’s reputation. What they revealed to the audience is that specific models of GM vehicles have specific cooling system contamination problems. And essentially, that DEX-COOL is not the culprit!
What was said at the presentation? Besides the video, Jay and Stede included their personal observations about the study. At the end, they fielded several questions from the audience. Here’s a recap of their entire presentation:
1. Keep the cooling system filled. In fact, fill the reservoir bottle to “Hot” level when the system is cold. Problems arise when a system’s coolant level is not maintained. (Fleet vehicles receiving regular maintenance, and with reservoirs kept slightly above normal, do not show signs of contamination. This even applies to the specific “problem” vehicles.)
2. The coolant problems found in this survey were caused by system contamination, and not due to the breakdown of DEX-COOL.
3. Check and keep the pressure cap clean and functioning. A contaminated and/or malfunctioning cap causes low coolant levels, which in turn causes overheating and a greater loss of coolant: the notorious vicious cycle. No matter what the vehicle, if the cooling system acts suspiciously, test the pressure cap.
4. On the ST vehicle models mentioned in the GM DEX-COOL video, you “must” replace all suspect radiator caps, especially those with a Drop-Center design, with a Stant Model 10230 or 11230 (Spring-Center type). (Just do it.)
5. Make sure that the coolant is at a 50-50 mix. Often, the flush water was not being removed from the engine block. Consequently, when a 50-50 mix is added to the system the resultant mixture could approach 30-70. Like any fluid that has been diluted beyond its recommended levels, the lowered level of inhibitors will not be able to protect the coolant system effectively. Low levels of inhibitors can cause pitting on aluminum surfaces and general corrosion of cooling system metals.
6. A safe method of achieving a true 50-50 mix is to first determine the actual capacity of the system (use the owner’s manual). Then add 50% of “that” amount of undiluted DEX-COOL (or any coolant), and top it off with water.
7. Mixing a “green” coolant with DEX-COOL reduces the batch’s change interval to 2 years or 30,000 miles, but will otherwise cause no damage to the engine. In order to change back to DEX-COOL however, the cooling system must first be thoroughly drained and flushed.
8. Bacteria cannot live in a hot, Ethylene Glycol environment and is therefore not a threat to DEX-COOL.
9. While there have been intake gasket failures on CK Series, V8 powered vehicles for various reasons, DEX-COOL has never been found as a cause.
10. Use a refractometer to check the condition of DEX-COOL. Its inhibitor package is strong enough that if the batch still provides proper freeze protection, it is probably still providing proper corrosion protection as well.
11. DEX-COOL can handle the minerals in hard water better than silicated conventional chemistry coolants. Drinkable water is suitable for top off.
12. In ST Blazer applications where the radiator cap is mounted at an angle to the ground, the vehicle is more susceptible to radiator cap contamination and its related problems. The Stant 10230 is a wise choice for these vehicles."
Joint GM and Texaco Report:
"GM’s Jay Dankovich and Equilon Enterprises’ (Texaco) Stede Granger directed a 2-year study of thousands of DEX-COOL cooled vehicles. Armed with the results, they really didn’t have anything bad to say about the coolant. In fact, they strongly defended the product’s reputation. What they revealed to the audience is that specific models of GM vehicles have specific cooling system contamination problems. And essentially, that DEX-COOL is not the culprit!
What was said at the presentation? Besides the video, Jay and Stede included their personal observations about the study. At the end, they fielded several questions from the audience. Here’s a recap of their entire presentation:
1. Keep the cooling system filled. In fact, fill the reservoir bottle to “Hot” level when the system is cold. Problems arise when a system’s coolant level is not maintained. (Fleet vehicles receiving regular maintenance, and with reservoirs kept slightly above normal, do not show signs of contamination. This even applies to the specific “problem” vehicles.)
2. The coolant problems found in this survey were caused by system contamination, and not due to the breakdown of DEX-COOL.
3. Check and keep the pressure cap clean and functioning. A contaminated and/or malfunctioning cap causes low coolant levels, which in turn causes overheating and a greater loss of coolant: the notorious vicious cycle. No matter what the vehicle, if the cooling system acts suspiciously, test the pressure cap.
4. On the ST vehicle models mentioned in the GM DEX-COOL video, you “must” replace all suspect radiator caps, especially those with a Drop-Center design, with a Stant Model 10230 or 11230 (Spring-Center type). (Just do it.)
5. Make sure that the coolant is at a 50-50 mix. Often, the flush water was not being removed from the engine block. Consequently, when a 50-50 mix is added to the system the resultant mixture could approach 30-70. Like any fluid that has been diluted beyond its recommended levels, the lowered level of inhibitors will not be able to protect the coolant system effectively. Low levels of inhibitors can cause pitting on aluminum surfaces and general corrosion of cooling system metals.
6. A safe method of achieving a true 50-50 mix is to first determine the actual capacity of the system (use the owner’s manual). Then add 50% of “that” amount of undiluted DEX-COOL (or any coolant), and top it off with water.
7. Mixing a “green” coolant with DEX-COOL reduces the batch’s change interval to 2 years or 30,000 miles, but will otherwise cause no damage to the engine. In order to change back to DEX-COOL however, the cooling system must first be thoroughly drained and flushed.
8. Bacteria cannot live in a hot, Ethylene Glycol environment and is therefore not a threat to DEX-COOL.
9. While there have been intake gasket failures on CK Series, V8 powered vehicles for various reasons, DEX-COOL has never been found as a cause.
10. Use a refractometer to check the condition of DEX-COOL. Its inhibitor package is strong enough that if the batch still provides proper freeze protection, it is probably still providing proper corrosion protection as well.
11. DEX-COOL can handle the minerals in hard water better than silicated conventional chemistry coolants. Drinkable water is suitable for top off.
12. In ST Blazer applications where the radiator cap is mounted at an angle to the ground, the vehicle is more susceptible to radiator cap contamination and its related problems. The Stant 10230 is a wise choice for these vehicles."
good info! 
Thread Starter
Team Owner
Joined: Sep 2005
Posts: 29,113
Likes: 2,194
From: Big Bend Country, TX
St. Jude Donor '06-'07-'08-'09-'10-'11-'12-'13-'14-'15- '16-'17-‘18-‘19-'20-'21
NCM Lifetime Member
I like this part best: 8. Bacteria cannot live in a hot, Ethylene Glycol environment and is therefore not a threat to DEX-COOL. At least my radiator is safe from my ex wife. 
