Just say NO!
Sealers that dry shiny are asphalt-based, such as Gilsonite -- a cutback asphalt with a solvent. Gilsonite salesman will tell you that oil base sealant is the best because it penetrates deep into the asphalt to rejuvenate and refurbish it by adding asphalt back into the oxidized surface. What they don’t tell you is that Gilsonite Sealer is much too hard and asphalt can become brittle and crack.
The sealer’s softening point is 200-210 F. The softening point of asphalt used for paving is 120-130 F. The Gilsonite Salesmen also won’t tell you the solvent dissolves and breaks down the asphalt binder. The Gilsonite wears away within a year and leaves behind damaged and weak binder. The original binder would be stronger if you had not sealed it in the first place. Gilsonite was the predominant sealer 30 years ago.
There are many Sealcoating companies and "fly-by-nighters" promoting oil based sealers. Most times, Gilsonite contractors won’t tell you what product they’re using - so ask. They have very little equipment overhead as they don’t need big tanks that agitate the product and they use a LOT less product per square foot. They don’t clean or edge the asphalt properly and they could care less about cracks, but their profit margins are very high. Just say NO! The industry standard is coal tar emulsion, don't be fooled into using an inferior product that can potentially damage your asphalt.