Curses, mag-chloride!
I have a hot water bib in my driveway. I hook a regular lawn sprinkler and hose to it spread under the vehicle and slowly drag the hose from one end to the other. Repeat a few times and it looks good, and you stay dry.
I love the ingenuity!
Finished washing my RV two days ago. Fortunately, the mag chloride wasn't as widespread on the undercarriage as I thought. However, it was stubborn! I don't have hot water available to spray and just spraying with cold water didn't remove it completely. I tried spraying P21S Total Auto Wash, let it sit for a few minutes, and rinsed. That did the trick for the most part! I still had to brush off a few places, but it came out much cleaner using the P21S. P21S is alkaline and everything I read says to use an acidic soap to remove road salt, including magnesium chloride. However, alkaline soaps supposedly help break down the oily road film that accompanies mag chloride. I remain confused...but at least with a little elbow grease my undercarriage seems pretty clean.
