Bruce...there is a distinction that I think you missed. I was talking about the garden variety Simple Green, but John's recommendation is better.

He shows the Aviation Simple Green that is not injurious to aluminum. Regular Simple Green may damage aluminum.

In the engine area there is a minimum of aluminum and I can only think of a few things such as the air cleaner to turbo inlet tube, the bands around the belt tensioners, the oil pan, the valve cover, the transmission housing, the DDEC housing and a few other things. None are likely to suffer any ill effects if you rinse them thoroughly, but that stuff is so good you may want to use if for other things such as cleaning hub grease off the wheels if you get a leak, and in that case you definitely want the Aviation Simple Green.

Here is just one source.

http://www.aircraftspruce.com/catalo...VB09-00809.php