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

First, this is an OEM part. That's what the manufacturer specified for my 2005 Silverado. Second, it is reasonably priced. Like many, I had the problem of coolant loss. Add coolant and after a few short cold/warm cycles (riding and then letting cool overnight, riding again) my coolant level started to drop. Top up again, drive a few times and the level will drop. After 25,000 km, the situation gradually worsened. When the problem first started I drove about 1200-1500 miles before the coolant drop became noticeable. Over the course of 25,000 +/- miles, that range dropped to less than 500 miles. After replacing this expansion tank cap, this problem is gone. I can't tell you how many hours I've spent trying to find the cause of this problem. We check the hoses, check the heater core, the radiator and even crawl around the block looking for leaks. Then the fear of internal troubles worries. $12 fixed. Problem solved. What's wrong with the factory cover? Dual o-rings allow fumes to "blow out” as these o-rings wear out over time. This vapor or water condensation is part of your "50/50 mix" of antifreeze running in your system. So the water is essentially "blown away" as steam, leaving only the antifreeze behind. This causes the liquid level to drop. Hope this helps someone with the same problem. This has plagued GM owners for a number of years now.