[STONEBOSS1]

Well I can tell you that when I took the car in for coolant flush/fill at a local Castrol quick oil/lube center. The car was hooked up to a machine that does this process. As far as the brand of coolant I cant say whether it was GM brand or aftermarket brand. I'm pretty confident that no air entered while it was in the process of coolant exchange. Again thanks for the really quick reply.