4 layers...damn, you beat my by one. With that much clear it's safe to buff it once every year without tearing down on the paint. Give it a good run with 3m compound (use the fastest buffer you can find, the $300 dollar one from sears is nice, but a bit on the heavy side), and then 2-3 runs with polish/protectant.
as far as that over the counter stuff they sell at the store, have fun with it every two months or so.
Try to keep your car out of the sun. And build a garage if you don't already have one
