Don't use regular antifreeze!!!!!! These LC engines use a mechanical seal to separate the water pump from crankcase oil. Most regular antifreeze has sulfates in it, small but abrasive particles that can and WILL wear away the mechanical seal. Honda blue coolant is good, cheap, and also premixed. I use Belray motochill in my b&w, also premixed. Any coolant made for motorcycles will be sulfate free.