I don't mind changing oil every 3-4000 miles, it's cheap insurance.
Like heck it is! The difference between a 3,000 mile interval and a 5,000 mile interval (which are both EXCESSIVE for a diesel) amounts to 40 additional oil changes at 300,000 miles, or about $8,000.
Push it to 7,500 miles, and you are over $12,000.
I'll spend $80 for an oil analysis a couple of times to save $12,000.
