i currently use castrol or pennzoil motor oil, but was thinking of switching to a synthetic. the truck has 59000 miles on it and i dont want to ruin anything. the truck sometimes sits 2-3 weeks between driving it so i want the best protection i can get.

 

I have no complaints with Amsoil. I don't see how you could ruin anything by putting Synthetic in it, Synth oil is generally regarded higher grade than the Dino you've been putting in it...

 

The only possible problem you could run into switching to a premium synthetic is that if there is a lot of sludge build up from the dino oil it could actually "clean" it too good and clog the screen or even the pump. It could also expose any small leaks in gaskets or seals that any contaminates would be masking. These are rare occurances, but possible.
I've always used synthetics, Mobil 1 for years and now Royal Purple with great results. On the few vehicles I've purchased used I always do the first change with a synthetic blend, kinda to ease the engine into synthetics and maybe to not knock off any contaminates too fast. Then change to a full synthetic at the next change, always within 3000 miles. Keep in mind, I've never read of any benefit of doing so, it's just what I've always done...

 

im switching to amsoil from dino oil next week. just put in 1/2 pint of seafoam to clean it out some before the amsoil goes in.