I live a little farther North than most of you so the taste of Fall is in the air. I know it was a 109% in Phoenix yesterday so you folks don’t worry about engine coolant freeze up but you do still need a clean and efficient cooling system. Flushing a cooling system is pretty simple the problem is to remove all the old coolant if you are going to change to a different type. The most you can hope to remove by draining is about 70% and this is by using a few tricks such as jacking up the rear of the vehicle and running it 30 seconds or so. Refilling the cooling system and warming up the engine will also help even doing this a couple times will remove more of the old coolant. The only tool available to the DIY, due to cost, is an air pressure driven vacuum tool, that will remove about 90% on a good day, this tool also makes refilling a snap as the coolant is drawn in by vacuum. Do not use GM orange lifetime coolant. In the test facility this worked great but the smallest leak that allows some air into the system can cause major corrosion problems. I use good old green anti freeze as with oil stick with a major brand they have a few more additives such as rust prevention and water pump lube . I also recommend A can of additive but not with a leak prevention feature. Any name brand water pump lube and corrosion prevention will work. I know this is a difficult for most DIY but properly dispose of you old coolant most cities have a hazardous waste facility where you can dispose of it.