Leaving the engine compartment as is without detail

I've used the Easyoff heavy duty in the yellow can for decades. Use it on a lot of things. It will remove the black rattle can paint from the motor bay while leaving the factory paint. Great on mild rust and grease. Use it on motor and suspension parts. Works great for removing paint from plastic like grills.
Will leave cast aluminum real dark so not always the best unless the part is going to be painted.
Never use on anodized aluminum unless your wanting to remove the anodizing.
It will remove the factory primer.