I'm not a big fan of engine additives and stop leaks,, and I'm sure others aren't either, so I thought I would post this. I have 1997 BMW 328i. The thermostat jacket is made of plastic on these cars and it broke. The car over heated. I changed the cover, the thermostat, and evenutally the water pump. I kept having over heating problems. This went on for about a week and half. Then I started notice the tell tale signs of a blown head gasket. Bad miss when you first start it until it warms up, a rough idle, loss of coolant with no visible leaks, and more than normal for the winter time, white vapor out the exhaust. Since it's really cold here and I didn't want to fool with changing a head gasket in his weather, and I also didn't want to pay an outraeous amount to have it changed, I tried Bar's Leak Head Gasket Fix. I bought the 31.00 bottle stuff because I didn't want to go to the trouble of flushing the coolant out and running water for the beter part of day. It's too cold here for that now. Anyway, This stuff works. I put it in let the car warm up. Then let it cool off and topped off the radiator. The second time I started it the rough idle was gone. I only have about 75 miles on it so far, but it's working. I'll try to find this post in a few weeks or a month, and give you guys an update.