I have heard that Amsoil is better. And if you can get it cheaper go for it. I actually use Royal Purple. My opinion on the oil change intervals is that the oil still get's dirty. No it doesn't break down like petroleum based oils but it does still get dirty. I use a high quality oil filter (Mobile 1 or K&N) and change it around 2500 miles, add a quart and go for another 2500. I usually only go 5000 miles between oil changes. I know it's overkill but I just can't mentally go 10000 miles between oil changes.
