How can a sealant possibly last more than five years?
Quick answer: Because a modern professional sealant is a polymer or synthetic-resin coating that cures into a hard, paint-like shell. Unlike wax, it doesn't melt or burn off -- it degrades slowly, and in favourable conditions can last well beyond its guarantee.
Modern professional-grade sealants have very little in common with traditional waxes, which only last a few months at best. A modern coating is closer to paint than to wax. It is built from polymers and synthetic resins, and once it has dried and cured it forms a durable shell over the paintwork -- or over any other substrate it is applied to.
Where a wax is soft and burns off in the sun, a modern coating degrades very slowly, and depending on the conditions it lives in, can last many years beyond the guarantee. The cured layer is chemically inert -- it does not react with the acids, salts and organic contamination that age unprotected paint -- and it is bonded to the clear coat at a molecular level rather than sitting loosely on top. That bond is what lets it survive years of UK weather, washing and motorway driving.
The headline warranty numbers -- 5, 7 or even 10 years -- are conservative estimates set by manufacturers who would rather under-promise than face complaints from owners whose coatings tired early. In our 30 years of experience, on cars that are properly cared for, coatings routinely outlast their warranties. For the full picture on what decides a coating's real-world life, see how long will a ceramic coating last?