bacon grease works with out any damage to paint! what i do is make a great big breakfast for the kids and put aside the grease from the bacon, later in the afternoon, i put the grease on the sap and let it sit for about 10 min, then wipe it off , depending on how much sap you have, you may have to go over it again.
go to the auto part store and buy what they sell for removing sap, bugs etc, I would be careful about using some solvents or even grease or oil. and I would definitely use a good paste wax after to restore the finish. A lot of the solvents will also remove the sealer and wax on the car to protect the surface of the car
To remove the tree sap from your vehicle's surface, you can use finger nail polish remover on a cotton ball. After the sap is removed, make a paste of water and baking soda to wash the affected area, then apply wax.
Another method to remove the sap is to use mineral sprits (it will also remove tar). Use a soft, terry towel, or wash cloth dampened with mineral sprits. After removal, wash the car and apply wax to the affected area.
Tree sap can also be removed by using a water-soluble paint brush cleaner. A common household solution is bacon grease or lard. Just rub it on, and off comes the sap. To get tree sap off of your hands, simply rub mayonnaise on them and wash it off. To remove tree sap and other substances, you can use common solvents like lighter fluid, rubbing alcohol, WD-40 or even Skin-So-Soft bath oil.