ThermoCure is left in the system whilst it is driven around with NO anti-freeze/coolant so one must remain mindful of freezing temps. It works through chelation (don't ask...I cannot explain it. Ha). Was recently able to solve an overheating problem with it on the original 40,000 mile block in a high dollar classic. Interestingly the problem started with only water in the cooling system for years in FL...remember what Nate said about how bad the system can get? Well he is VERY correct. It took three applications of the ThermoCure but magically after the third round it launched a bunch of crud into a clear filter we had put into the upper hose and now it runs cool. We were starting to look for another block.

Nate, Does the citric acid require water only or can you have coolant in it?

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