I've successfully used ordinary rattle-can clear coats, both enamel and lacquer. Enamel in matte and gloss. All have worked well on engine and chassis parts, although I haven't used them on anything high temperature like cylinder or heads or exhaust flanges or pipes. I HAVE done 'normal' temperature engine bits like cases, clutch / ignition covers, and head bits like points covers and valve covers. All good, no problems, no reliability issues.