use hi temp engine enamel that's available in spray cans from auto parts stores.
The major key is surface prep tho.
Make sure that you get ALL of the oil and grease off of the areas to be painted.
You can use a solvent like brake-clean to spray the parts down before you paint. let the parts air dry thoroughly before you paint.
After you get them clean don't touch them with your bare hands because the oils from your skin can cause the paint not to stick.
once the paint is dry, start the engine, let it build some heat and then shut if off.
let the engine completely cool and the paint will be cured.
I painted the jug on my engine 2 years ago and this is how it looks today.