We do both oil and water

Mr.blacktop was the first contractor to tape around house walkways and walls. 

(Oil base)    Oil base sealer is the best for driveways from the ages of 1-10 years old. if your driveway has alot of cracks this is not what kind of sealer you want to use . Oil base sealer is the same thing your driveway is made of. when is sprayed on your driveway it sinks in to the pavment un-like water base. this help's the driveway stay flexable .A driveway is always moving and expanding due to frost or from driving. So the more flex the less cracks you will get. Also what oil is great for is if your need to fix a spot on the driveway you can re-heat the blacktop and blend it where you cant notice it. 

(Water base)   Water Base sealer is great for a driveway with many cracks , oil leaks , and lots of missing stones due to power steering marks. The bad things about water base is that to much of it could make the driveway look like it is starting to crack but there is a good chance this is the sealer cracking not the blacktop. The reason for this is that since water and oil don't mix ( Which your driveway is made of oil ) that the water base don't sink in it forms a layer on top of the driveway. So when your driveway starts to flex due to nature the sealer will crack