Disclaimer have never used Opti-cote.
From what I understand it is a decent product, but hard to work with. I think that is why professional application is suggested.
My thought is there is no silver bullet to magically keep your paint looking good. If you wash your MINI regularly & keep some wax on it the paint will hold up. I use Prima Hydro with every wash. I also lay a coat of Prima Epic on twice a year. Hard to say what corrective measure you will need to do before you lay any wax on.
Wish Dave O was here, he's very good at this stuff.
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