[whatsnewell]

Steve and Tom, I use Simple Green's heavy duty solution (it is actually kind of purple in color) at 50/50, let it soak for a few hours and then spray off from outside to inside just like Steve. This last time I was able to use my friend's commercial pressure washer with a heater to really clean off the inside fins, and get all the gunk that seemed impervious to the Simple Green off completely. Engine is running about 6-7 degrees cooler now.