My bay was quite filthsome and I never knew what to do to clean it. Some local CEGers suggested some fomay engine cleaner stuff. I forget what it's called but it was in the wash/wax/cleaning section at Pep Boys. A couple bucks for a can, you spray it on, let it sit for a few minutes, and then wash it off with a garden hose. It took care of the majority of the grunge that had built up for three years.
