Sealcoating is maintenance, not repair. It is a coat about the thickness of a coat of paint, and there is a long list of things it does not do. Here is the honest version, including the times we tell people to keep their money.
Sealer protects the surface from water, fuel and ultraviolet light. It does not bridge a crack, it does not carry weight, and it does not put a base back under a driveway that has lost one. If you have any of the following, sealing over it is money spent hiding a problem for about a month:
Those are patching, infrared repair or resurfacing jobs. Seal after that work, not instead of it.
This is the one most people have never heard. Sealer does not soak away. Every coat sits on the last one, and a driveway that gets done every single year builds a thick layer that goes brittle, then cracks in its own pattern and peels off in sheets. Once it peels you are looking at a patchy black and grey driveway that looks worse than bare asphalt, and the fix is grinding or stripping it, which costs more than the sealing ever did.
A residential driveway in this climate generally wants doing every two to three years. A drive that sits in shade, carries two cars and has no fuel drips can go longer. If a contractor is offering to come back every spring, that is a schedule that suits him.
Sealer needs to cure, not just dry. The surface is walkable in a few hours and usually ready for a car in 24 to 48 hours depending on heat, humidity and shade. Park on it too early, or turn the wheel hard while stationary in high summer heat, and you get scuffs and tyre marks in the new coat. Walk across it fresh and you will carry it into the house on your shoes.
Plan the day. If both cars have to be on the street overnight and that does not work for you, it is worth waiting for a week when it does.
A fresh coat makes an even driveway look excellent and makes a patched one look like a patched driveway that is now black. Seams, old repairs and different asphalt ages still read from the street, because the texture underneath has not changed. If your reason for sealing is that the driveway looks like a quilt, sealing is not the answer you want.
Driveway sealers are broadly either coal tar based or asphalt emulsion based. Coal tar sealers contain polycyclic aromatic hydrocarbons, and a number of cities and a few states have restricted or banned their sale over concerns about runoff into waterways. The rules vary by place and they change, so the useful move is not to take a side on the internet, it is to ask your contractor which type he is putting down and to look it up for your own city if it matters to you.
Ask about dilution at the same time. Every sealer has a maximum water ratio printed on the drum by the manufacturer. Going past it makes the drum cover more driveway, looks black on the day, and takes years off the coat.
We would rather tell you to wait a year than take the job twice. If we look at yours and the honest answer is not yet, that is what you will hear.
None of the above is an argument against sealing a driveway that needs it. Asphalt fails from the top down, and it fails because of three things: water getting into the surface and freezing, ultraviolet light drying out the binder that holds the stone together, and fuel or oil softening it. A coat of sealer is a barrier against all three, which is why a maintained driveway outlasts a neglected one by years rather than months in a climate that freezes and thaws as often as Ohio does.
What it is not is a way to postpone a repair. The useful way to think about the difference: sealing is what you do to a driveway that is still sound, on a schedule, so the expensive work stays years away. If the expensive work is already due, sealing over it only changes what it looks like from the street until the next winter.
Next: the four tests that tell you whether yours needs doing, and what it costs in Dayton when it does.
