Had a new (rebuilt?) pump installed last week. When I picked up the car the indie had the hood up, the A/C on, and the car idling. The temp gauge was at 90C. The tech said "pretty good for idling for 45 min. with the A/C on". I agreed. However, I noticed driving over the weekend that the temp runs at 90C, without air on, around town. Before the pump the temp ran just over 80C. I was shocked to see the green coolant when I picked the car up, especially since I had gone to the dealer and bought a gallon of MB coolant before dropping the car off. Left it in the floorboard. Should I as them to change it out? Will it lower the operating temp? The tech said it was important not to mix the coolants, but that the green was okay. They did not change the thermostat out, only the serpentine belt.

Thanks, Dave