I've used Zaino before, it's good stuff but very expensive. There are a lot of other car sealants and waxes that yield just as good or better results for a lot less but Zaino seems to have the magic formula that has a nice gloss and last a long time between applications.
If you car has a lot of swirls and scratches you'll need to polish up the car first with an abrasive otherwise it won't look it's best. Zaino Z5 is a filler so it can mask up fine swirl marks but deeper imperfections will still show.
They have a lot of new products since I last used them like Z-PC, ZAIO, Z-PC, Z8 Grand Finale Spray.
If your truck isn't too bad with swirls you can wash, clay, apply ZAIO, Z5 w/ ZFX, Z2 w/ ZFX. waiting 1 hour between each application to allow it to cure before wiping off. They recommend applying Z6 gloss enhancer between each coat of Z5 and Z2. Like stevenredx said you should layer multiple coats to achieve the best results.
If your truck has a lot of swirls it is recommended you have a buffer to help speed up the process but you can remove swirls by hand. I've never used Z-PC polish before so I don't know how abrasive that is but there are tons of great polishes on the market that are fairly cheap. My favorite combo at the moment is Meguiars 83 Dual Action Cleaner and 80 Speed Glaze on mild to medium swirls or just 80 on light swirls.