Can I use any car wash soap in a foam cannon?

Technically yes, but the difference between a soap that's marketed for foam cannons and a generic shampoo is dramatic — cannon-friendly formulas use surfactants that whip into thick, clinging suds at low dilution. Mr. Pink, Maxi-Suds II, HydroSuds, and Turtle Wax Hybrid Pure Wash are repeatedly singled out in foam-cannon discussions for sticking to vertical panels long enough to give the soap dwell time.