Take off the serpentine belt and inspect it for cracks. If there are many cracks or missing pieces of ribbing replace the belt. Other things to look for while the belt is off, try turning the tensioner and idler pulleys to see if they squeak, etc... Some have had problems with the stock tensioner fatiguing over time so it may need to be replaced as well.
Yeah, simple green works well just make sure your engine is cool and don't let it sit on anything aluminum for more than a minute as it will etch it. I like to use orange degreaser... don't have to worry about etching aluminum... Here's a couple before/after pics on my DD after using orange degreaser and dressing with Stoners Trim Shine...
1. Cover any electrical connections with aluminum foil
2. Spray orange degreaser liberally over all surfaces and let it dwell for a few min
3. Agitate soiled areas with a brush
4. Hose off and towel try to avoid waterspots
5. Run engine to dry off remaining water
6. Spray dressing of choice (i usually use ArmorAll tire foam on my mustang engine, works really well.
I just got my tranny rebuilt, reason I want to take even better care of my car. Even though mechanic said it wasn't from beating on it, which I rarely do.
The planetary gears just broke apart.
So now, after driving a rental for a week missed my Mustang so much and want to baby it even more.