Pontiac Grand Prix 3800 series 3. Daughter's car. She recently had her cooling system flushed and Valvoline Max-life was put in. I pulled the lower radiator hose and drained what I could (where is the radiator drain plug?), to change her water-pump. After pump was changed, I mistakenly filled system with full-strength Havoline Dexcool. It took about 7 quarts. What should I do? Should I take it back where the flush and fill was done, and have them do it again? The two things that concern me are the mixing of the two different coolants, even if they are compatible (not sure), and the concentration of what's in there now. Thanks for any advice you can give me.