A while back I redid my civi-gasser's valve covers and intake manifold but before I took 'em in for the powder coat, the guy at the shop told me to clean them up real good with oven cleaner--- yep liquid oven cleaner. And after that he said to use this phosphate liquid stuff that you cut 1-to-3 w/water and just paint it on, then rinse w/water and let everything dry 24 hrs. Bought a gallon at Home Depot. Anyway, the phosphate leaves a white-ish coat, but very light. So whatever he did after that in his shop, it made the parts turn out absolutely perfect.