Dawn dish soap will work wonders and is very cheap (think birds and oil spills).
Warm engine (not operation temperature hot). Spray soapy water, let sit for 10 minutes or so and rinse.

Go gentle on the water...no pressure!

2002 s
 

I used GUNK all purpose cleaner and degreaser concentrated. (not the foaming type)
had to do mine twice, light spray of water. I clean all my car engines about every two years, makes it easy to see any leaks before they get to be a big problem. :cheers: