I never trust the "lasts 5years" crap. There is no wax that lasts that long... hell I doubt there's a wax out there that last a year.
I worked at dealerships... they don't use good wax. They use bulk crap wax that barely lasts a week.
Even the paint sealant they sell... they fail to tell you it doesn't last as long as they say it does and it needs to be reapplied after like 6 months or something and you should keep a good coat of wax on it to help it last longer.
Caranuba wax you can tell the quality by the caranuba %. The higher then percentage the longer it will last and the better it will shine. Most off the shelf waxes are around 20% and will last about a month. If you go to the higher end waxes such as the supernatural, RBOE, or the best wax in the world (or something like that i can't remember it's name... something gay) they're all around 44-55%. Supernatural is rated to last 8-12 weeks... that's 3 times longer then any off the shelf wax. Granted you're paying like $120us for the tiny tub BUT if you're using it correctly you will use a very minimal amount and it will last you probably longer then 6 bottles of off the shelf wax would. Hence making the all around buy a better one in the long run (if you can shell out the initial cost).
I don't trust any wax that says it will last over the 4-5 month period. There are some that will... but I doubt you'll get any more then a year at most out of them and even then I wouldn't trust it enough to not wax my car for a year.
I've also got the straight DoDo juice... I applied it to my entire car including my windshield and windows in February and even after having the car painted my windows STILL bead like you wouldn't believe. Only now is it starting to weaken a little bit.
I've got supernatural on our Lincoln LS, I did it back in like April... the car does a lot of sitting... I only take it to the barn once a week and we drive it here or there in between, so needless to say it doesn't get washed as often as I find more desirable. But every time I wash that car the water STILL beads like it was just waxed.
My Trans am... which is red and has no clear coat... it's a single stage paint. Back in March was waxed in RBOE. Car hasn't been washed since. Any other wax my headlights turn pink from the sun in about a week or to... only now are they starting to fade a bit...
Moral of the story... if you want a good long lasting wax you're going to have to shell out some cash but in the long run it will last longer both on your car and in the jug. Do your research but be skeptical of the "miracle" waxes. Most decent quality company's wont come up with false claims.
Google caranuba wax shops or auto geek. They both have very informative websites for auto detailing.
Hope that helps!