I use NAPA OE Asian Red coolant, $15 a gallon on sale. The Zerex was cheaper, but went with the NAPA one. You're going to have to replace the coolant at a shorter interval, after the initial change, anyway due to the fact that you can't get all of the old coolant out of the heater heat exchanger radiator in the passenger footwell. So you'll have a mix of fresh and some old coolant in there. Posted via the PriusChat mobile app.