Asphalt is made up of binder, oils, rock, stone, and gravel. The binder holds these components together. When new asphalt is laid it is normal for oils to oxidize out which will make the pavement stronger. Experts suggest sealing your asphalt parking lot 90 days after the asphalt is laid to slow down the oxidation. After the first application of sealer it is then suggested to seal your asphalt every 2-3 years after that. There are many things that contribute to oxidation: sunlight, rain, air and chemicals being the most common.