Is there urgency to rinsing the undercarriage after beach driving or is doing so every few months sufficient? NB: I have not done Fluid Film or anything else to the undercarriage yet.
Gotcha, thanksThat's a bit of both. Obviously it doesn't have to be done instantly, but I wouldn't go for months without rinsing it off. Salt is a terrible catalyst for rust/corrosion. Basically salt draws moisture to itself, and the water expedites the oxidation of iron based metals.
So by leaving salt on the vehicle, you're speeding up the corrosion process. A few nights isn't likely to make a noticeable difference, but a few months probably will. Especially if you routinely go a few months without rinsing the salt off.
Why is the salt different in Texas than Florida, New Jersey, or California?Different areas are worse than others. Texas beach salt is horrific and you'll pay the price if you don't wash really good on the same day. You might get away with more time in other areas