Engine compartment color

I say any means you have to remove the oil, grime,.. wipe down with auto body
" wax- oil remover", I have even used laquer thinner,too......(Forget the crap made to "seal" over the rust with...I call BS) clean off rust best you can, wire wheel on drill, wire cup on right angle grinder,kill rust with phosphoric acid solution ( commercial Ospho),,,, spray it with self eteh or epoxy primer, tp coat with a good urethane or enamel ( have fond a cheap way for this is Rustoleum as it has high % of solids).Undercoat over that..... I have even used that $32 large spray can of epoxy primer sold at O Reilly's, works pretty well. BUT There is NO substitute for PRO automotive primers and paints! IMO