They say asphalt only lasts about 25 years in a parking lot. I seal coated my lot once in 33 years, we did it ourselves and it was a bitch. It took about twice as much material has what it said on the can. Looked good for a few years after that. Now it looks like I’m going to have to redo the lot, it looks like alligator skin, when that happens it’s past it life. Asphalt work is expensive, we had to redo the entrances and exits of the all the bays and redo around the catch basins, I believe that project was about $4000. Call around for a quote.