I had this Procare match a price on a coolant flush given by a competitor. After getting the job done, I was on the highway 1/2 hour later and my "low coolant" light came on. I called them and they offered to take a look at it but I was already going the opposite direction. I had to stop at a gas station and buy coolant. I figure the last time a coolant light should come on should be immediately after having the system flushed.