s10, I would tend to agree with you on that. I thing this stuff was designed for very hard running engines like for racing just to help the coolant system maintain the thermostats set running temp. Since it is $10/qt premixed (read $5/qt water) I will pass on it. Not having trouble now, why bother. We'll just see what my buddy does with it. Thanks all. BTW, wardog, thanks, good link.