87 vs 89 octane

[CAMDENN]

I use 89. I've heard that 87 is the reason they had a lot of oil consumption issues with the older 5.0L's. Could just be a rumor. That's the reason I use 89.

I see no reason to go 91-93.

…Definitely a rumor.

 

[Wile_Coyote]

I run 91 in mine and have since I bought it

 

[Aandrews109]

Have run 87, 89 & 93 in my ‘23. It definitely runs best and gets better mileage on the 93. Made two trips to the same destination over the past 1 1/2 months. 87 first trip yielded 19.5 mpg. Second trip on 93 yielded 21.5 mpg.
However, as someone else said, don’t think the mileage makes up for the extra cost.
I definitely run at least 89 when towing.

 

[Edzecc1]

New 2026 5.0 Tremor. After purchasing and leaving the dealership I was told we filled your 36 gallon tank for you. They felt the need to tell me they filled it with 87 octane and that that was all I needed. Even the filler cap boost 87 octane. Put 1500 miles on locally and felt the truck getting sluggish from day 1. Was leaving to go to the shore for a 2 week vacation and decided I would take the truck on a 200 mile 1 way trip in 95-100 degree summer weather. After reading posts made by fellow 5.0 Tremor owners I filled the truck with 93 octane from Mobil. Boy what a difference. Great ride. More power than I ever felt and averaged 20.6 MPG all while driving 65-70 with AC on. Might be more expensive but from now on 93 is for me. By the way I love the truck, traded in a 2024 Bronco Outerbanks with SAS package, 35’s , 2.7 twin turbo. Lux pkg,. Whole 9 yards, thought it was my last new vehicle I ever needed. Was I ever wrong. Yrs I know they’re 2 different vehicles but I think I found the right the one now. More room and all the truck I need.

 

[James Dean]

I've run 87 in mine since new. After reading the posts I'm going to try a tank of 93

 

[money4nuttn]

I only use 93 from Exxon and yes, my engine runs very smooth. Also, I pour a 32 oz bottle of Techron into the tank every other month.

When do you add the Techron when it's empty and then fill it up or fill it up then add it or does it matter?

 

[TheWaterman]

New 2026 5.0 Tremor. After purchasing and leaving the dealership I was told we filled your 36 gallon tank for you. They felt the need to tell me they filled it with 87 octane and that that was all I needed. Even the filler cap boost 87 octane. Put 1500 miles on locally and felt the truck getting sluggish from day 1. Was leaving to go to the shore for a 2 week vacation and decided I would take the truck on a 200 mile 1 way trip in 95-100 degree summer weather. After reading posts made by fellow 5.0 Tremor owners I filled the truck with 93 octane from Mobil. Boy what a difference. Great ride. More power than I ever felt and averaged 20.6 MPG all while driving 65-70 with AC on. Might be more expensive but from now on 93 is for me. By the way I love the truck, traded in a 2024 Bronco Outerbanks with SAS package, 35’s , 2.7 twin turbo. Lux pkg,. Whole 9 yards, thought it was my last new vehicle I ever needed. Was I ever wrong. Yrs I know they’re 2 different vehicles but I think I found the right the one now. More room and all the truck I need.

Just want to make you aware, the throttle and trans are adaptive. If you drive it very conservatively for a while, the throttle and trans programs itself that way. So a lot of that is probably it starting to feel sluggish over time. A lot of people notice this new, because they drive conservatively for the break-in.

The reset process is:

- Ignition on, but don't start
- Give it a couple seconds to clear the lights on the dash
- Pedal to the floor, release for 3x
- Turn the truck off

That resets the throttle mapping. You want to talk about waking it up, that does it. You get that crisp throttle response again.

Just so you know, I fill with 89 (in NJ) and average what you are on the highway. 20.5 - 21 mpg. I've never put 93 in the truck.

I won't fill 87, but I go with 89. Occasionally I'll top off with 93.

 

[CAMDENN]

When do you add the Techron when it's empty and then fill it up or fill it up then add it or does it matter?

If you only get the regular / small bottle, add it when you’re at a 1/4 of a tank and then fill up.

After the first time, it really doesn’t matter when you add it but remember, the smaller bottle only treats up to 15 gallons.

I only purchase the 32 oz bottles and I add it at a half a tank then fill up. Then reason that I add it when I’m at half a tank is because I never let the tank get pass half because I don’t want to see the sticker shock of filling up a 36 gallon tank when it’s almost empty.

The 32 oz bottles aren’t sold everywhere so keep that in mind.

 

[TheWaterman]

When do you add the Techron when it's empty and then fill it up or fill it up then add it or does it matter?

Prior to adding fuel/filling the tank so it washes down into the tank from the filler tube.

 

[SubyEvo]

Just to update this thread, I've ran 91 the last probably 20+ tanks. Fuel economy has increased and the 5.0 engine seems happy.