Wet 1500 - 2000 grit is OK for minor sap removal & oxidation. Forgot to mention for heavy and/or dried globs of sap : Kerosene will disolve tree sap and won't do any harm to auto paints. Wash car 1st to remove sand particles, then use sponge with Kerosene to dissolve sap . If sap has dried well, let Kerosene soak on sap for a couple of hours. Then wash with soap & water. While we're on the subject: Bird droppings will ruin all paints where they land in 2-3 days. Wash off droppings as soon as they're noticed.