i've painted engine accessories like air cleaners, pulleys, fans, with the rattle can version, but on the block it self i would only use a engine enamel, i would'nt want to expirement with the rust paint and have it not hold up to the heat. i have had really good luck with duplicolor engine enamel in a rattle can, in my pics, both the beetle engine tins were painted with it and it looks just like when i did it, also keep in mind that those VW air-cooled beetles run HOT, over 400* deg F, and the paint is perfect after 6 years.