Oil the Bearings
Remove the skateboard wheels from the trucks. The trucks house the axles and hold the wheels to the skateboard. Remove the hex nuts from the ends of the axles and take off the wheels.
Remove the bearings from the wheels. Use a small flat-head screwdriver to gently pry the bearings out of the wheels. Each wheel has two bearings. Remove all eight bearings.
Remove the shields from the bearings. In some bearings, the shields are held in place with a thin c-ring. If your bearings have c-rings, pry them out with your screwdriver. Pop the shield out by gently poking it from the other side of the bearing with a straight pin. Be careful not to damage the shields.
Soak the bearings. Place all eight bearings, as well as the c-rings and shields, in a bowl with either a solvent, such as acetone, or a biodegradable detergent. Use enough solvent or detergent to completely cover the bearings. Allow the bearings to soak until they are clean.
Allow the bearings to dry. Once the bearings are clean, remove them from the solvent and place them on a paper towel to dry completely. If you used a detergent, rinse the bearings thoroughly with water, and then set them out to dry.
Oil the bearings. Add only a few drops of lubricating oil in the spaces between the ball bearings. Roll the ball bearings around with your finger to make sure oil is evenly applied. The type of oil you use is up to you.
Reassemble the bearings. Put the shields and c-rings back in the bearings, put the bearings back the in wheels, and put the wheels back on the trucks.