I say Yes, the 10-30 is fine for us Long Islanders. From everything I have read you can interchange synthetic to non synthetic and back without any mixing problems. I don't know about the 7000 miles though. My opinioun: oil, synthetic or not will still get dirty, The filter change at 3000 WILL help but you are still getting particles past that filter. I might go 4000 with the synthetic but not 7000.

My dad goes that synthetic route but I don't. I have 230000 on a Chevy pickup with no engine work done on it and I have a Jeep with 200000 with only a head job. My '89 240 has 186000 on it and it's chugging along just fine. I've checked the valve shims for wear and it wasn't even enough to consider doing. So I'm not convinced you gain that much from synthetic oils. I think on my cars the engines will outlast the bodies.