The whole car?
I recommend you wash the all the bare metal in a Metal Conditioner first.
After that, lightly scuff off the white residue with a 3M Scotch Brite. Then Spray Epoxy primer.
Some will say Ospho. My 2 cents is they're all phosphate based. I bought my metal conditioner at the ACE hardware. 1 Quart should do a whole car once diluted. Nasty stuff on your skin.
Make sure you ask the paint supply store that you want to buy a "Direct to metal Primer"
There are many brands and prices will vary. I used Five Star Extreme. Pretty good stuff but on the higher pricing. About 60 bucks for a Quart kit. Versatile since it can be done as a Sealer, Epoxy, or just a prime depending on how you do ratio.