If your asphalt surface is stable and was installed correctly, it will need to be sealed only occasionally. Sealer comes in 5-gallon cans, enough to cover about 250 square feet. You'll find that older, porous drives will soak up more sealer than newer drives. A good sealing will make gray-looking, dried-out asphalt look better while keeping out water that causes erosion and cracking. Many homeowners mistakenly believe that sealing can take the place of resurfacing. It can't. Resurfacing involves topping an old asphalt drive with at least 2 inches of new material. And no coating can rescue a job that consists of a 1- or 2-inch layer of asphalt applied over loose gravel.