I pour/pump directly in the heat exchanger. A couple of gallons coolant, couple of gallons water. Trying to keep a 50/50 mix going. When the last gallons go in, when it comes down to the final gallon / quarts, I error on the side of more water.Hi.what kink of coolant goes in a 12v71n? Do you poor it directly into the filler cap on the heat exchanger?