Exterior Cleaner

[Jowilly]

Does anyone have any experience with this product "Vertglas Fiberglass Gel Coat Restoration System"? Purchased an older Montana from an inlaw and it needs a little TLC on the outside, some oxidation and black streaks, any advise would be helpful, just don't want to damage the finish and make more work for myself. I realize this is going to require some elbow grease and several hours/days to get done so anything that would make this job easier would also be helpful, this was just one product I found, there may be others that are better and easier.

Thanks