I cant help my self 3000- 5000 mile max is all I can go after that I feel bad about it even on my 7.3 diesel 15w40 convention in that. Good syn. in everything else not allways the best Amsoil XL or Mobil one, but it would be be a real waste for say amsoil ss good for 25000. Oil is the most easy maintenance to do and maybe the most important. I like it clean and full. I remember in the 80s amsoil did the 25000 thing just change the filter more often I new a few that where doing that didn't work out so great your under there drop that dirty oil. I can see oil analyst on big truck marine engines they 10-20 gals or more of oil change when needed $$$. So you have a engine with 4 oil changes in 100,000 miles doesnt make much sense for 5-6 qts, of oil. Just a note may be a good idea to look over a car for problems before every 25000 miles. I was a mechanic for over 35 years and draining dirty oil always gave me at least a little feeling of doing something good for the car its easy dont forget the few grease fittings out there is not many out there any more but on the bigger stuff. I was board just my 2 cents