Hi, in 2015 on our cross country trip, I guess-timated about 10.8 MPG. Now I'm on another trip and wanted to try something. I have read where some people lock out 6th gear while towing. I have never done this because my truck has plenty of power and no problem what-so-ever towing my trailer in 6th gear.


I set my cruise control at 60 MPH and reset my mileage meter. Then I did the same thing, but with 6th gear locked out. My RPM was slightly higher and so was my gas mileage. So now on this trip I have locked out 6th gear. My first tank was 11.5 MPG and so far on my second tank I'm getting 13.0 MPG.

 

You need to zero odometer and record exact amount of gallons of gas used, the speedo computers are not that accurate IMO. But not lugging engine can help depending on route sometimes.

 

Question.? How do you "lock out" 6th gear.?

 

On my truck I can lock out all gears by shifting to M then select the gear I want to be in with the +- button on the shift lever.
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Leave it in "D", then simply click on the - on the gear shift, which displays all gears. Then hit - to lock out 6. It's in your manual.

 

I have noticed the same increase when using 5th for towing, even at 75mph.

 

Hi, 2,500 miles and no conclusion. Side winds and head winds killed my mileage on this trip. The mountains didn't help either. So I can't say whether I will tow in fifth or sixth on my next trip.

 

Fuel consumption is NOT just related to rpm. It is related to rpm and throttle position. Look at the ike videos where they are WOT (wide open throttle) at 3500 or 4000 rpm. You'll see them get like 5 mpg. Engine efficiency is not constant either.

When you tow at too low of rpm you can be so deep in the throttle that your mpg will suffer. That is why picking the right gear/rpm can make a 10-15% difference. In my 6.2L F150 pulling around 7k I always lock out 6th. I get 1 mpg better doing this. I tested it both ways early in my ownership each for around 1000 miles on I40.

I've never owned an eco-boost but from the web, they are fastest towing, do great with mpg when not towing, but use the most fuel when towing. I would think finding the right gear could be even more important on the eco but I don't know.

 

Yep, you gotta let it breathe a bit to get the best efficiency.

 

Shhhhh the eco crowd doesn't believe in hear swaps because they have enough torque to do whatever you need them to when equipped with the 3.31s from factory!

Disclaimer: I have an ecoboost with 3.55s and 35" tires and will do a gear swap to a lower gear ratio when funds are available. The engine is turning too slow and thus, not as efficient as its almost always in boost to maintain speed.