GPSman1 wrote:

"With full synthetic oil, you can change oil every 15,000 miles."

And

"I used Mobil 1 and took it 15,000 miles the second time, and the oil was still in good shape. Visually, it was still clean, dark-tan colored, and translucent, after 12 months and 15,000 miles."

This he wrote in another tread, but I thought of restating it here.

Even though I agree that full synthetic oil last longer than non synthetic oil, I would still not recommend going to 15,000 miles between oil changes. This is mainly because Ford recommends part synthetic and a max of 10,000 miles between oil changes.

When I took my FEH in for the reflash of the PCM, I had about ~9,500 miles on Mobil One 5-20W oil. The Tech said all my fluids looked good, but said my oil looked like it was needing a change. It so happen I was going to change that oil the weekend my FEH broke and had the oil and filter ready to go. I personally would not exceed the max miles of 10,000, even with Mobil One with the low RPM's and amount of EV driving I do.

Does Mobil One oil say it's okay to exceed manufacture specs between oil changes?

GaryG