Imjust recieved new fenders for my 15 Roadster. I want to prime them tomorrow to prevent rusting. I noticed they are covered with a light coat of oil. What is the best way to remove the oil prior to painting.
I washed mine with lacquer thinner,twice, and use clean rags each time.
After cleaning the oil off with lacquer thinner, use some etching liquid on them so the primer will adhere, or use self-etching primer.
I use DuPont 5717S metal prep, available here from O'Reilly. Pricy, but good stuff.
Wash well with lacquer thinner to get most of the petroleum off the metal. Then metal prep using a paint brush to get all the cracks and folds clean. When metal prep hits bare steel it should lighten the color of the steel a couple shades. If it doesn't, go back and clean more with lacquer thinner. Lacquer thinner alone will not open the surface enough to allow primer/paint to adhere. After metal prepping the surface thoroughly, wash off the metal prep with water and a hose. Be sure to get all of it out of the cracks and folds. Immediately dry the part using compressed air and a clean towel. Blow the cracks and folds completely dry. The metal will look stained or discolored. That is natural as it now has no protection, so prime straight away. If you have done a thorough job any type of primer will adhere.
A note on parts that have been left exposed and have developed surface rust and fingerprints while being fit on the car. As long as they have not come in direct contact with water you should be able to clean them with metal prep and a scotch brite pad using the above method. At some point the rust will not respond and you will have to look at media blasting or chemical stripping. However I have cleaned parts left exposed, but not wet, for 15yrs, and had them come out fine. Just took a little more elbow grease.
The best way to prevent surface rust from forming after rinsing off the metal prep with water, is to quick dry the fender using a heat gun. Milwaukee makes a good one one with 2 settings 700 degrees F and 1,500 degrees F. I have one of these and it is very useful! I also use it to remove old paint from wood siding on my house, down to the bare wood, prior to painting. I checked and ebay has numerous heat guns for sale at very good prices (much less than what I paid for mine, new). Jim Patrick