My engine compartment is due for a good cleaning, so I picked up a can of engine degreaser at Pep Boys. However, I am having second thoughts on spraying this stuff on it. Is it safe or does is discolor any parts? Also, when rinsing off, is it safe to spray the hose around the engine compartment? Maybe I should play it safe and just use something like Simple Green? Should I cover anything with plastic bags, etc? Any advice would be appreciated.