I'm looking to clean a few years' worth of oil, dirt, and other deposits out from my engine compartment. I've read that it's possible to simply use a coin-operated car wash to hose off the engine, but need to know what precautions to take beforehand. I know there are a few non-waterproof components that need to be covered up, I just don't know what they are. If anyone knows how to go about this, or if there's a better way to do this, please let me know. Thanks...