I've done detailing in my engine bay and elswere on my car the paint I use is call DUPLI-COLOR METALCAST , if I remember well it come in 6 different colors ,it work on alluminium,ss,or steel, the part to be painted has to be very clean , apply a sligth layer first once dry keep on painting until you get the desire hue ,that paint is very tuff will withstand higth temp and can be wrenched once dry ,anyone can check ernie9944 engine details on bbs and see what I mean the color I use was red also it has a anodized colour effect ,the paint is heat,oil and gas resistant. just hope I was helpful sharing my experiences