I haven't used it on a motorhome. But, I used it for 20 years or so on my trucks. To be honest, I continued to have some rust issues even with the Ziebart applications.
I switched to Fluid Film a few years ago and actually like the product better.
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2017 Jay Feather 7 22BHM Baja/Andersen WD
2018 F150 4x4 3.5L Ecoboost Max Tow
2015 MB Sprinter 2500 Passenger 2.1L Diesel
2007 Ram 2500 4x4 Cummins 5.9L G56
I had a 73' el camino dealer rust proofed, not by Ziebart, but I almost feel it accelerated rust when it peeled and trapped moisture.
X2 on fluid film, it works well. Only drawback I have found is it attracts dust and dirt.
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2020 Pinnacle 32rlts
640 watts solar, 300AH lithium
2020 High Country Duramax 3500
TS3 Hitch
Ms says I'm full of useless knowledge and other stuff...