Since we have gotten away from the original subject, I can throw in a couple of things about the Opti-Seal.
I haven't used the Z-CS or the Ultima, but the Opti-Seal seems to be a very good product.
It took me one application to learn how to apply it thin and that seems to be the secret to not having any streaking
The first application I made, I had some streaking, but was able to get rid of those streaks by going over the area again with the Opti-Seal. A QD might have done the job, but I didn't try it. I didn't want to add the QD to the mix of the Opti-Seal. I'm not one to experiment with mixing different products. I leave that to the chemists.

My later 3 applications went fine without the streaking problem. As is often the case, I think the streaking was an operator problem rather than a product problem.
The look is very nice. Not necessarily better than anything I have ever seen, but I don't think you will be disappointed.
One thing I did notice was how easily the dirt washed off the Opti-Seal treated paint. (The vehicles do still get dirty

)
The price is probably up for debate. The 8 oz. bottle wasn't really cheap, but the stuff goes a loooong way.
I have done my Montana twice, (once with too much), the Gran Prix once, and a 19' boat once.
The bottle is down possibly 1/2 inch after those 4 uses. It probably took some where around 1/2 to 3/4 of an oz. for all of them.
The actual cost per use seems to be very low, it's just the initial price for such a small bottle that made the stuff seem expensive.
And yes, Troy does have it.
New! Optimum Opti-Seal with Applicator 8oz - New Arrivals
Charles