Fuel grade for Ford V6 4.0 Liter SOHC

I am looking at buying a Ford Explorer Sport with 143000 miles on a V6 4.0 Liter SOHC engine. The SUV has a lot of pickup. The guy that is selling it says he fills up with premium gas about every three tank fulls and uses regular the other two times. Is the engine supposed to run on premium gas?


No. At that mileage, though, he might have enough carbon buildup in the combustion chambers that it may knock slightly with regular, although the knock sensor should prevent this. I had that problem on my '95 Suburban once it got over 100k miles. Ask him why he does it.

It’s desgined for 87 octane. The seller is just wasting his money and/or he’s just trying to impress you.