Be it a brand-new treadmill or a used one, you should lubricate its belt, and it is a mandate. What most manufacturers recommend is to apply oil to the machine even before you start using it. Though some treadmills get lubricated after they come out of the factory, they may have to sit in the warehouses for a couple of months before they arrive at the final customer. During this time, the lubrication can break down and become sticky. This may degrade the performance of the treadmill.