2018 GT MPG 87 vs. 93 octane

ice445

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The car will run fine on 87, Ford did a good job with the knock detection and timing tables in that regard. You WILL lose power especially under back to back runs, hot days, etc. And unfortunately the stock knock detection routine on these cars will pull a LOT of timing and keep it held back for a long time, so I don't know how anyone claims that the car makes the same power on 87 unless they don't ever accelerate, or only use it in the winter or whatever.





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accel

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The car will run fine on 87, Ford did a good job with the knock detection and timing tables in that regard. You WILL lose power especially under back to back runs, hot days, etc. And unfortunately the stock knock detection routine on these cars will pull a LOT of timing and keep it held back for a long time, so I don't know how anyone claims that the car makes the same power on 87 unless they don't ever accelerate, or only use it in the winter or whatever.
There's a thread here at the forum with consumer reports article discussion testing cars on regular vs premium including s550. HP difference is literally very minimal.
 

ice445

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There's a thread here at the forum with consumer reports article discussion testing cars on regular vs premium including s550. HP difference is literally very minimal.
Under ideal circumstances, sure. Fool around on a 100 degree day and it changes pretty quick.
 

Ebm

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There's a thread here at the forum with consumer reports article discussion testing cars on regular vs premium including s550. HP difference is literally very minimal.
Yes, it was a study done by AAA.

Don’t Be Fueled: Premium Not Always Worth the Price | AAA Newsroom

Testing was on a 2015-2017 Mustang GT. The difference in horsepower between regular and premium gas was 3.2%. If your 2017 Mustang GT was rated for 435 horsepower on premium gas, it would get 421 horsepower on regular gas. A very small difference when you consider how much regular versus premium gas affects the Mustang Ecoboost.

With that said, several variables have changed between the Gen 1, Gen 2, and Gen 3 Coyotes. While the Gen 1 and Gen 2 have a 3.2% different in horsepower between octane grades, the Gen 3 is a different compression ratio and it also added direct injection so it is hard to tell if or how much the percentage would change on the 2018+ GTs.
 

Qcman17

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I've sort of settled in the middle on this using only 91 in my GT. I was using 94 initially but its more expensive of course. 91 is working well too. Every once in a while I think I'd like to try 87 just to see what it does but I always chicken out :)

But with the extra knock sensors on the Gen 3 and the DI I don't think 87 should hurt it but I just can't bring myself to run it either.
 

Dfeeds

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There's a thread here at the forum with consumer reports article discussion testing cars on regular vs premium including s550. HP difference is literally very minimal.
Too bad for consumer reports that it's your low and mid range torque that suffer the most when using a lower octane. There's a reason why people say peak numbers don't tell the full story.
 

ctandc72

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It's your car, your money - do what you feel is best. Is 87 octane going to hurt the GT? Under normal driving conditions - I highly doubt it. Thing is - I didn't buy my GT for gas mileage. And the few dollars per tank difference in the cost to get a quality 93 octane gas is worth it - TO ME.

Will 93 octane make power than 87? Yes. Is that power readily noticeable without a dyno - doubt it.
 

Zelek

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Why did someone have to come in and bump this thread... :facepalm: Let it die.
 

OldPhart

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Hi - I think a lot of threads have a longer than necessary life because so many of us are suffering from Covid induced social deprivation that we find ourselves with so much extra time on our hands that these forums give us something to occupy our minds and time. My post is a fine example of worthless drivel to pass the time until dinner on a cold and windy winter day... Bruce
 

Coosawjack

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I agree "OldPhart" but seriously.......why would anyone buy a $30K to $60K "PERFORMANCE CAR" and try to run 87 Octane fuel to save a few pennies......sounds NUTZ to me?? 🤔 :shock:
 

Bikeman315

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I agree "OldPhart" but seriously.......why would anyone buy a $30K to $60K "PERFORMANCE CAR" and try to run 87 Octane fuel to save a few pennies......sounds NUTZ to me?? 🤔 :shock:
Because not everyone beats their cars on a regular basis. 87 is just fine for around town with an occasional blast or two and for long boring highway trips. It's not my thing but there's no reason not too. Saving a few pennies here and there is how the rich get richer.
 

Mr Hyde

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I live in Florida i ca definitely tell the difference in over all power band and performance of the car it feels sluggish and shifts poorly when using 87 There is a noticeable overall decrease in responsiveness and overall drivability vs 93
 

Coosawjack

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Because not everyone beats their cars on a regular basis. 87 is just fine for around town with an occasional blast or two and for long boring highway trips. It's not my thing but there's no reason not too. Saving a few pennies here and there is how the rich get richer.
Personally I'd drive less if it hurts too much to buy 93 Octane....by the time you mix all of it together you have no idea what you have IMHO!! 🤔

Do as you wish Bikeman but for me it's 93!! :thumbsup:

How are things up at Myrtle??:)
 

boos550t

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i ran 93 for the longest

But then i realized i don't even drive this car hard at all so I was just throwing my money away. Maybe a pull on a on ramp here and there but that's it. I can't remember the last time i went over 100mph. Sounds like I should've just bought an ecoboost lol.

So I went back to 87, and haven't noticed a fuel economy dip.
 

Bikeman315

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Personally I'd drive less if it hurts too much to buy 93 Octane....by the time you mix all of it together you have no idea what you have IMHO!! 🤔

Do as you wish Bikeman but for me it's 93!! :thumbsup:

How are things up at Myrtle??:)
Hello Jack. Things here are just fine thank you. Hopefully will be able to get down to Savannah this year and may drive through Beaufort to get to Hilton Head. By the way, I'm with you. Always use 93. But not everyone feels that way. Just want to be understanding.
 

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