is there anything i should look out for? is it ok if i spray the motor down? i also got simple green APC for degreasing and removing tough corrosion

I use a nozzle set to "flood" for a lot of water and little pressure in order to avoid getting water where it didn't belong.

Don't know if Simple Green will corrode aluminum, but you might not let it dwell too long and be sure to rinse it all out.

See - http://www.detailingworld.co.uk/forum/showthread.php?t=43031

I should add, I clean my bay with Meg's APC and follow it up with CD-2 Engine Detailer.

Use Pledge wood polish, I'm Serious.

this should probably be parked up top!

I'd be interested in this too, the 4 cylinder E36 engines get alot dirtier I think, they don't have the plastic covering you can treat over most of it.

Whatever you use, if it isn't intended for underhood use, make sure that it isn't flammable.

Honestly, when I bought my car it was very clean under the hood. Theres a couple of tough spots I had to use a magic eraser on, but a quick detailer and old microfiber do the trick for me.

I also keep things slick by dressing with a tire gel.

FWIW, whether it can be done safely or not, I'm very reluctant to spray water under there.

Spraying water works, but I cant do it to any of my cars anymore. My supra hell, if I did that Id have to shoot myself and on the M the last thing Id want are for some electrical units to go bad. If it was a hooptie, well thats another story all together. Id get engine-brite, spray the bitch down, and hose it away.

I have sprayed mine down everytime i wash the car with no issues. Im a huge fan of Oil eater(got it at checker) Spray it on let it soak for a few minutes,Spray it again and wash off with as much pressure as possible.If anything go to the car wash and spray it down with the pressure wash. try not to soak coilpacks,plug wires or distributer. Rise off any paint it may come in contact with. i rinse the bay off every wash dirty or not to remove dust or anything in there. Its easier to clean if its not that dirty in the first place.

I use a small amount of water one spot at a time.

I accidentally got my alternator pretty wet and nothing happened..