FYI...I have used K & W Headgasket sealant in my daughter's car with a pretty severe head gasket leak and it is still going strong after 2 years. The only difference is I put it in and drove it for 500 miles vs. running the heater and idling it on high for 30 min, then draining it and letting it dry over night. My friend recommended I try it and I only used an $8.50 bottle. I don't know how it works, but it does. You just have to make sure you don't let it sit overnight or during the day in freezing temps because you just have water in it!