Schaeffers 7000 or 9000. Pulling truck here at the shop has 9000 in it and hasn't had the oil changed in 2 years. Motor was down on compression in 1 cylinder when it was installed, 655hp, 2 years later with 25+ dyno runs and probably 75 sled pulls on it and it's still going strong. Oil analysis shows it's still got some life left on it before it needs changed. But in all seriousness, 7k-10k on an oil change is EASY as pie. Figure up what it cost to change the oil every 4k-5k with rotella and compare that to 10k mile intervals on Schaeffers and there is no cost difference.