I prefer my engines to be one color, rather than a bunch of colors.
I'll make an exception on valve covers & big pans for race motors, or of course Hemi valve covers.
Maybe that's the "underplay" old street-racer thing, or the restoration influence, or trying to be artsy.
Been painting the race motors grey forever, since working on an old ex-Penske TransAm car.
Kind of an industrial look, and easy to see if anything escapes a gasket.
Never liked the staining or white corrosion that bare aluminum gets, arouses my OCD