Review on ACDelco RC98 15 P.S.I. Radiator Surge Tank Cap - GM Original Equipment by Paul Rosemark

My 2000 Malibu with GM 3.1 V6 was losing coolant. I've gone through all sorts of checks and tests and figured the problem might be a bad head gasket or something more expensive. I did not look at the coolant cap as I recently replaced the expansion tank and cap with a non-original unit. Looking at the aftermarket cap, I actually saw damage to the bottom o-ring. As soon as I put that on, the coolant leak stopped and the expansion tank stopped overflowing. The bottom o-ring appears to be more durable and a better fit than some aftermarket covers. For an additional $2, it's worth buying a genuine factory part.