i used steel wool on my mani, and it shines like its brand new. a steam cleaner as airguard350 said isnt a bad idea either.

 

Steel wool will take away the protective anti corrosive finish!

 

The only think im gonna say is don't spray directly on the coil packs, especially the push in types. I would also pull them out after washing the engine and dry them off because they aren't water tight and having water on them for long periods of time of course creates rust, and rust will destroy the coil pack blah blah blah.......

 

not if u treat it afterwards