Undercarriage

Recently just did my yearly fluid film under truck being that I beach drive a lot in hatteras. (Live in Va).
Something I’ve always wondered - I always rinse underneath after driving sand but is it necessary with the frame fluid filmed? Notice sometimes the water takes it off. Tia

 

I use woolwax, and on their FAQ they recommend driving in a dusty environment to cover the woolwax with a layer of dust and dirt. I usually take a short cut home after I apply the woolwax down gravel roads, and then the outer layer isn't as messy since the dirt gets rid of the tackiness, if that makes sense. If you drive down a dusty road before hitting the beach, the sand would stick less to the coating. I will say though in the winter in the rust belt, I go to a car wash and still do the underbody wash. The woolwax doesn't get washed off in that. But I do use cans of fluid film to touch up areas I miss sometimes, like this year I managed to miss the back bumper. The fluid filmed areas tend to wash off where the woolwax doesn't. If you want to rinse, might be better to use woolwax instead, but getting a dusty layer over the fluid film would help limit how much sand sticks? Not really sure since I don't drive on sand, but I do notice after getting covered in dust, the woolwax doesn't pick up too much salt residue in the winter.