Shell Rotella T 15-40, approximately every 3000 miles in my N/A 6.5
I'll second the previous comment about Fram filters (there's that article out there somewhere). I prefer AC filters.
As for running long intervals on oil changes, I prefer 3000 mile intervals... oil breaks down thermally - hydrocarbon molecules break down into shorter chains; thereby decreasing viscosity, film thickness and a host of other lubricating properties. Not to mention contamination of the engine oil by blowby. Oil filters after 10k miles are probably either Swiss-cheesed, just short of plugging up, or both!