I have a 2006 F-150 4X2 daily driver with about 145,000 miles on it. 4.6 engine. I have been running Mobil 1 Extended Performance 5W20 and Motorcraft FL820S oil filter. Changing over to Mobil1 1 EP oil filters. 8000 mile oil change intervals. Since Mobil 1 EP oil is guaranteed for 15,000 mile oil change intervals, I assumed that if I stick with 8000 mile change intervals that would be overkill. After reading a few things here and there, I am wondering if I should go to 5000 mile intervals with Mobil1?

I just bought another 2006 with a 5.4. I won't let that one go past a 4000 mile interval.

 

Think I'll send an oil sample to Blackstone Labs next time I change the oil in the 4.6.

 

With EP oil and filter, in a 4.6 I'd change at 10k or 1 year, whichever comes first.

 

Thanks. I figured 8000 miles was overkill, and that's what I'm looking for.