Sorry, I should have provided more info. Is a bare metal I am priming and is part of the floor pan and will be covered with carpet and etc. Don't want to wash it with Dawn and water to cause flash rust. Naptha is more like coleman fuel very good on cleaning grease. So I though since is a floor pan, naptha to remove the oil contaminations and Alcohol to remove water based contaminations. But if it will be a bad idean. then I will not do it.Bare metal? Painted? Fiberglass? Plastic? Greasy or oily? Silicone contamination? Lots of variables, including how much you care for the panel you are spraying. In other words, I would not experiment on something I care about. Dawn and water is safe to use on most anything.
I have read in a few places that denatured alcohol leaves some kind of residue. is that true?do the naptha first then use denatured alcohol. denatured makes a good wipe down and final cleaner before paint. if you have iso alcohol like jl said then that is fine as well