I change the oil in three Ford Panthers and one '06 V8 Explorer twice per year. None go over 5K in that year. One 2006 Lincoln TC Designer (Garage Queen) stays in the hundreds, so I sometimes let that one go a full year. ALWAYS use Motorcraft 5W20 Blend from Walmart for all of them with the Motorcraft filter. On the last purchase I noticed the Supertech full synth was actually a little cheaper, so I'm kicking around switching. The highest mileage vehicle is still under 150K. Would it be best to stick with the Motorcraft blend? Worried the full synthetic may break loose deposits, or some other issue. But, if that's actually a better oil, and cheaper, why not?