Good God. This is "more than you could ever stand to know" about radiator caps. I got a stock-looking cap from Nick that doesn't say Made in Mexico on it. Then, a dime-store recovery tank at the Auto Zone where everything is made in China. Then fill to TWO INCHES from the top with new green coolant. 180 stat. Never had a problem. Does not piss/purge.

The first Cruise in Spring usualy shows the puddle beneath radiators due to owners that can't resist topping off.