Sorry to hear about your engine. I'm on my 2nd engine. But only because Toyota forgot to put oil in the damn thing after I paid for an oil change. They bought me a new one for free
Anyways, here's some thoughts:
Half of your problem is putting Synth oil in right from the get go. You have to run your car on regular oil for about 30K miles to let the valves, pistons, etc seat properly. Synth oil protects too well to allow proper wear-in on the engine (a certian amount of wear is good). Plus, did you break the engine in at all or did you just jump in and pound it? It takes about 1500 miles of easy driving and 2 oil changes to break the engine in properly. When you say premium gas, are you talking 101 octane or 91 octane or what? Check your owners manual, it's designed to run off of a certian octane only. Just food for thought for the next engine you put in it.