For engine bays, i suggest some thick paints if not some coats of clear would be good to protect the paint from unwanted fluid. as for rubbing the engine bay, you could use scotch brite but if your more keen use 800 grit paper. From what i've seen alot of people spray their engine white aposed to other colour, i guess it looks more clean but needs alot of maintance. acrylic colours are the way to go for engine bays and interior.