I know it is a little late in the season but I thought a few words about anti freeze are in order. I use regular ethylene glycol, I have considered the environmental safe alternative, but feel that more info is needed. I have a dog and do worry about leaks but I keep a close eye on it. I am also set in my ways. I also do not use dex cool, it worked well but if there was a leak and it allowed air into the system it caused a major corrosion problem. GM has instituted a refund program to reimburse owners. When to flush is also a concern with dex cool as it always looks clean. To check for parasitic or residual voltage, caused by the interaction of 2 or 3 metals in the engine, cooling and heating systems. Place the black lead of your voltage meter, set to the lowest scale, to ground the red lead in the coolant. There should be no voltage or no more than .05 of a volt.This will also work with ethylene glycol but normally the condition is an accurate measure of when to flush. If you have a problem with corrosion in the cooling system check for voltage if it is present in fairly new anti freeze check your grounds. I used to do my own flushes but I just don’t like the idea of the coolant entering the river, it is also illegal in many states. So now I have it done. I try to do it every other year. I also do not use recycled anti freeze, where they clean and reinstall your old anti freeze. No reason I just don’t like the idea and have my doubts it works. If you do your own flush be sure to open the heater control valve, on vehicles with automatic air it will be necessary to bring the engine temperature up. Using a chemical is OK but only necessary in badly corroded system. Also if the heater core is badly plugged flush it separately and it also helps break loose the corrosion if you open and close the hoses by using a pair of pliers to give the fluid a chug, chug and it will break the gunk lose, have patience water is cheap.