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BurbMan's avatar
BurbMan
Explorer II
Jul 02, 2019

What Fuel Do You Use in Your EcoBoost?

So last year we got a 2018 Explorer Sport with the 3.5L EcoBoost, the same motor they put in the F-150's that a lot of guys tow with. (The Explorer is not on towing duty, we still have the Suburban for that.)

The owner's manual says to use whatever octane of fuel you want, but that the engine will perform better on hi-test. We've been putting only 93 in the tank and it runs great!

This month Car and Driver runs an article about "Are you wasting money on hi-test" and it looks at 4 examples of vehicles, one of which was the F-150 with the 3.5L EB. Apparently the PCM uses the knock sensors to "measure" the octane of the fuel...the PCM advances timing until it detects knock, then backs it down until no knock is detected.

The results of the C&D test were that the EB was the only engine tested to significantly benefit from the higher octane fuel, as measured by +20 hp, +1.5 psi boost, and -0.5 sec in the 1/4 mile. Fuel economy at highway speeds was also 0.5 mpg better, although it was noted that this in no way makes running 93 an economical option. It costs more to run 93 no matter how you slice it.

C&D also noted that the truck ran fine on 87, no knocking, hesitation, or other symptoms of poor performance, but it felt slower in daily driving.

I'm curious if you guys that run F-150's are using hi-test, and if not I would suggest you give it a try.
  • This is a case of YMMV. Everyone's driving styles are different.

    Over the years I've owned several "premium optional" vehicles. One of them got the same mileage and performance on mid-grade (89) as on premium, but far better performance than regular (87). Mileage was the same with any of them. At the time mid-grade was only 10¢ more so it was worth it.

    Another car got better mileage with premium. At the time gas was $4 a gallon and premium was 20¢ more than regular. Doing the math I saved about $200 a year using premium. Now premium is 40¢-60¢ a gallon more and gas is far cheaper. I no longer use premium in that car.

    That said you have to test it yourself. Comparing and Explorer to an F-150 is not apples to apples. I suggest running two tanks of regular. Carefully record the mileage. Take note of acceleration and passing ability on the freeway. Run the second tank close to empty. Run 2 tanks of premium and record the same observations. Then you'll be able to better decide what's going to work for you.
  • Our 2015 Expedition with the 3.5 EB has plenty of power running 87 octane. Not going to spend that much extra for fuel when I don't need to, simply because it "feels better".
  • I've got 89K miles of towing and daily driving on my 2016 2.7 EcoBoost F150.
    I have run both 93 and 89 octane when towing and I can't tell a difference. When not towing, I get over 20mpg on 87 octane and only a tad more mpg if running a higher octane.
  • My sister also has an Explorer Sport, with almost 70,000 miles. She runs premium too.She tows occasionally (17' ski boat) but mostly she likes the better performance. There is a noticeable reduction in throttle response lag, especially in warmer weather.

    I've pretty much found the same in my Focus EcoBoost.Fuel economy benefit is there but slight (about 3 MPG in mountain driving, not much different in town), but also a noticeable performance benefit. In hot weather, it noticeably pulls timing at low and mid RPMs at WOT. Plus I tow a utility trailer on occasion as well, and the Focus EcoBoost requires Premium when towing. It's not just recommended like the 3.5L.
  • I asked the same question a little while back:
    3.5 Ecoboost fuel

    I am running a 2016 model with max trailer tow package at rated capacity and have plenty of power. I have thought about running a test with premium just to see what the difference is but I am a cheapskate and when I see that $0.60 to $0.80/gal difference I say to heck with it, I really don't need to be driving any faster with that much weight behind me anyway.