Interesting Oil Change View

My DD is a 2005 Jeep Rubicon (4.0L), and my wife's car is a 2003 VW Jetta TDI. I have settled on 10,000 mile change intervals for both vehicles. Oil samples have indicated that I could comfortably stretch this out to 15,000, but 10K is a nice easy to remember interval. I use Mobil 1 5w40 "Turbo Diesel Truck" in both vehicles. The Jeep has 120K miles, and the VW nearly twice that. Both run like new. The "buy good oil and run it longer" theory seems to be working out for me.