Hi there guys and gals. I used one of those block testers with the blue dye and the color changed from blue to green. So looks as if I'm at the beginning stages of blown head gaskets or a warped head. I also see small bubbles in my coolant. Anyway, I'm going to give the blue devil pour and go a try. Most companies leave out crucial info on their directions. Has anyone used this before. Are you supposed to have the heater on full blast while you add it slowly so it circulates through the cooling system and block better ?