How long does liquid car wax actually last?

Expectations vary by chemistry. Across specialist detailing subreddits, pure carnauba liquids are generally reported to last a few weeks to about a month, while synthetic sealants and SiO2 hybrid liquids are commonly cited at 8–12 weeks or longer with regular washes. UV exposure, wash frequency, and whether you top with a spray sealant all materially affect durability.