You can brush the meatballs with oil before baking if you like, but I didn't include that in this recipe because I don't think it's necessary. I tested this out by brushing only half the batch of the meatballs with oil before baking. Then, after baking, I asked my husband to see if he could tell a difference between the oiled vs. non-oiled meatballs (without telling him which was which). He couldn't tell a difference either in appearance or taste. So, brush or not, the choice is yours. They will taste delicious either way!