Flex Fuel Gas Question
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Cross-Country
Joined: Oct 2021
Posts: 61
Likes: 4
Flex Fuel Gas Question
I have a 2020 F-150 and have been running mainly 87 octane, but am going to occasionally switch to the Premium gas when I plan on towing (from what I hear, there is a difference in towing with the Premium versus the 87 octane).
My question is, is it okay to mix 87 with Premium gas? Meaning if I have half a tank of 87, is it okay to mix it with the Premium gas OR should I run as much of the 87 out of the tank & then fill the tank up with Premium.
Basically, I'm wondering if it is okay to mix regular unleaded with Premium gas. I won't do it often, mainly when I'm towing. Thoughts?
My question is, is it okay to mix 87 with Premium gas? Meaning if I have half a tank of 87, is it okay to mix it with the Premium gas OR should I run as much of the 87 out of the tank & then fill the tank up with Premium.
Basically, I'm wondering if it is okay to mix regular unleaded with Premium gas. I won't do it often, mainly when I'm towing. Thoughts?
Moderator
Joined: May 2005
Posts: 8,210
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From: San Antonio, TX
You can mix the fuel with no problem. That’s how they make mid grade at the stations, buy mixing regular and premium at the pump. But you will get the most benefit by waiting until the tank is nearly empty. It will take about 5 minutes of driving before the higher octane fuel is fully circulating.
Lead Driver
Joined: Nov 2020
Posts: 7,128
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From: Sportsman's Paradise
Depends entirely if you're running a custom tune or not. If no, then no problem mixing octanes. If custom tuned you'll need to use what ever octane fuel it's set for or risk engine damage.
Tuned
Joined: Jan 2015
Posts: 472
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From: Southeast Wisconsin
Depending on how much weight you are pulling, you may not even need premium fuel. I tow between 4K - 7K lbs and have not felt the need for 93 octane, even in midwest summer heat with my 5.0 engine. I also saw no difference in mpg when using 93 either. In my case, the only difference between octanes was that my wallet was lighter after a high octane fill-up.
Fleet Mechanic
Joined: Jan 2020
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I said heck with it, I run mid grade all the time. I also tow my 6k travel trailer in the summer, honestly I have no problems at all with mid grade. I have run 93, might get 2 mpg better, not worth the extra $. I am a believer and top tier fuel though, no more of that grocery store crap. Yes, you can mix all you want, stay away from that 85 and 88 stuff.
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Cross-Country
Joined: Oct 2021
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Great. Thanks guys. Appreciate the info. I'm towing a 4,000 fishing boat throughout the Spring, Summer and Fall. I've only been using 87 octane, but will try using Premium and see if there is a difference. Sounds like no one really notices it. If I don't notice a difference, I will stick with using 87 or even 89. I'm glad you can mix tanks as well. I wanted to make sure that was okay before doing that.
Elder User
Joined: Apr 2011
Posts: 627
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From: Orange County, CA
Hey webs, what engine does your truck have? just curious...
Some good answers to your question here. Folks in these parts have a lot of good experience with towing and such. I think you have it figured out already, but best of luck to you.
Maybe in the future you could post up some pictures of your rig towing that boat. That would be awesome.
Some good answers to your question here. Folks in these parts have a lot of good experience with towing and such. I think you have it figured out already, but best of luck to you.
Maybe in the future you could post up some pictures of your rig towing that boat. That would be awesome.
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Cross-Country
Joined: Oct 2021
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Karlsgems, I have a 5.0
I would've shown a pic of my truck/boat, but I have my boat stored in the garage for the Winter. I live in the Chicagoland area, so we unfortunately won't have soft water for another couple months. It's hibernating right now. Counting down the days until Spring!
I would've shown a pic of my truck/boat, but I have my boat stored in the garage for the Winter. I live in the Chicagoland area, so we unfortunately won't have soft water for another couple months. It's hibernating right now. Counting down the days until Spring!
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Junior User
Joined: Feb 2010
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I run 93 in my 2019 3.5 all time time as its only driven on the weekend and during the summer it pulls the boat. Stay away from using the term flex fuel, as flex fuel is technically indicative of running E85. Not sure about the 5.0 but the 2.7 and 3.5 cannot run flex fuel
Logistics Pro
Joined: Oct 2004
Posts: 4,738
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From: FL
The 2018+ 5.0s benefit greatly from 93 octane (or higher) fuel. I switched to 93 when testing out theories on some light knocking I was getting under low rpm, high load situations running 87. Fixed the knocking.
Truck has noticably better throttle response and downshifts less on 93.
Truck has noticably better throttle response and downshifts less on 93.
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