They say it takes 200 hours to polish a trailer. I think that may be a little conservative! Our trailer has a lot of filiform corrosion that would not compound out with Nuvite F7 or F9, so we are wet sanding those areas first with 400/800/1000 grit paper then compounding over it with F7. That filiform is some bad stuff! If anyone has a better method, please share! The F7 is doing a great job of removing the normal corrosion and scratches. We plan on using a Cyclo with Grade C next, then Grade S. We might be done by Christmas! It will be worth it though…look at that Shiney Hiney 🙂