Simple green works great for keeping the motor clean, but FYI only, after 2 or 3 times my lettering started to come off on the valve cover. Not a big deal, but now 1. 5 years and 6-8 washing later my valve cover is straight black. My process has been soaking simple green (50-50 mix) for 5 minutes and rinsing off with a garden hose - no pressure. Works great. I do cover my AFE filter and the filter for my Pac-Brake compressor.
Tim
04. 5, Pac-Brake, Banks six gun, AFE, Pro Guard 7 w/ torque tube

Tim
04. 5, Pac-Brake, Banks six gun, AFE, Pro Guard 7 w/ torque tube