Well my old 2004 has 160.000 miles, sorry I'm not looking for 25 mpg, and I'm old school. That 5.4 uses oil pressure for things other than just oiling, I use High mileage 20W50, motor is as quite as a flat head V8. It's mine and paid for, sold my 1988 F-150 with 497.000, guy I sold it to wrecked it but was still running

 

20w 50 is a little thick for most areas john........ your in south Texas and can get away with it ............ I still think that's pushing the limit.

 

If you want to know how long you can run between oil changes send oil sample to Blackstone. In a week or so you will have all the information about your engine health and oil life. Cheap insurance and will let you know if something is going south.