I have developed my own foam gun system. I use the foam gun to presoak the car while I clean the wheels. Then before I start washing a section of the car I soak it again with the foam gun with the idea of having plenty of lubrication to cut down marring. I use the Optimum Car Wash in the foam gun and typically wash the car with Meguire's Gold Class. I love the Optimum Car wash so much that I might just switch to it entire once my entire supply of car washes is used up.