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Hello I realized today after beating my head about my car's overheating problems that I have the wrong coolant in it.

About a year ago, my car ran dry. At the bottom of the expansion tank was an orange crust(also the manual recommend DexCool.. ). I ignored the Dexcool warning in my manual as one of those "you also need to take it to a certified dealer to get the oil changed" type of warnings. So I filled it up with green coolant. Well, reading up more I realize that I'm wrong.

About 6 months ago, I had a wreck and got the radiator replaced(salvaged) and the mechanic(who I'm convinced now is an idiot) filled it up with green coolant along with leaving several leaks. I took it to another mechanic and after fixing the leaks, he also filled it up with green coolant.

So I've been running green coolant for about a year now. How exactly should I go about switching to the proper Dexcool coolant? Would it do more harm than good to switch now?

Also, my car is having problems in that it overheats when sitting in traffic or idling. It doesn't have problems when going 65MPH or so. Could this cause this kind of problem?

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Earlz
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3 Answers3

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As long as you don't mix the two coolants together you should not have any problem. I run "green" coolant in my GM that came with Dexcool, and have been for more than 5 years. You do want to check the ratio of coolant and water as straight coolant (or too much compared to water) will not cool as well.

To answer your question I wouldn't bother switching, if you decide to do so anyway simply flush the system and refill with the coolant of your choice.

To address your overheating concern, if it only overheats sitting still you need to check the fan operation and the shroud around the fan and radiator. Another possibility is the water pump, I have seen the fins wear off and the water pump stop circulating coolant, if yours is starting to do this it may not be circulating enough water at the lower RPM's at idle.

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The overheating is likely caused by a non-working fan. When you are speeding, the air you run into cools it, but in traffic the radiator experiences no flow. As far as the coolant, you can have it flushed with the DexCool again, but personally I run BMWs blue coolant in my S10... So the coolants all work the same, and Chevrolet just prefers the red. Theoretically, you likely have no DexCool left after so many people have messed with your system, so it should be OK.

Edit: Also, as pointed out, ensure your radiator does not have any crushed tubes, or bent fins, as this might make it extremely inefficient. If it was not the right part number, than it might not cool enough fluid to meet the needs of your vehicle.

FossilizedCarlos
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If the green coolant is dexcool compatible, then there's no pressing need to switch. Most (but not all) off the shelf pre-mixed coolants are compatible with just about everything and can even be used for topping off systems full of other coolants. However, topping off a red/orange system with green will tend to make for funny brown looking coolant that could potentially mask other problems (hard to check for coolant contamination if it's all nasty looking already).

Brian Knoblauch
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