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I've heard mixed reviews on the forums (from googling) on what gas to use for the ST.

I understand 93 Octane is best for performance as it keeps the full HP of the car, while using 87 drops it about 8 HP.

I just got my car, and im mainly using it to commute to work and back (50 miles a day) mostly on the northway.

I kinda dont feel comfortable using 87, as im worried it could hurt my engine/car in long term. Im wondering if 91 is a better bet as i dont need the 93 and the gas milage difference isn't worth the extra price.

Also, all gas stations around my area use ethenal.

What are your guys opinions?

Thanks!
 

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I've heard mixed reviews on the forums (from googling) on what gas to use for the ST.

I understand 93 Octane is best for performance as it keeps the full HP of the car, while using 87 drops it about 8 HP.

I just got my car, and im mainly using it to commute to work and back (50 miles a day) mostly on the northway.

I kinda dont feel comfortable using 87, as im worried it could hurt my engine/car in long term. Im wondering if 91 is a better bet as i dont need the 93 and the gas milage difference isn't worth the extra price.

Also, all gas stations around my area use ethenal.

What are your guys opinions?

Thanks!
Before anyone else has the chance, you will probably get asked why you didn't Google search this since it's been asked hundreds of times. Basically it's personal preference. If you feel better using 93 then use it, you'll get better MPG to make up for the loss you would take using 87. Therefore if you live in an area where the difference between 87 and 93 is only like 20-30 cents then you might save money using 93. Now if 93 is 40-50 cents more like where I live you are spending a few bucks more to run 93...but I want the extra power and it's my personal preference. Your car so you can use any gas you feel comfortable paying for.

Edit: Now that I'm tuned for 93 I don't have a choice, but still used it as a reference. Also, I see that you did Google this now that I reread what you said so ignore that.
 

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I have run 87 when not tuned and my mpg end up about the same. When tuned I need to run 93, big difference in the car with a tune, but I really cannot tell a difference using 93 without a tune.

Car is made to use either in stock form so run what ever you are happy with... probably boils down to $. Here in NC it is 0.60$ more per gallon or ~6$ a fill up or ~300$ a year, worth every penny with a tune! For me in stock form cannot tell a difference so 87 it is!
 

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I am running 87 in the winter because 40 cent diff and I am in Upstate NY so snow. No need for more power. Once time hits for my Summer Tires it is back to 93.
 

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If i wasnt running a tune i'd probably be running 87. I felt no performance loss when stock, and the ecu will make timing adjustments to resolve any possible ping


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I just used the app to find 93 octane stations near me. Nearest one is 45 minutes away, 3 others over an hour away. If you look at a map of the US, there's almost a solid line through the midwest, East of that line everyone has 93, West, we're ****ed. :(
 

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I run 89 instead of 87 On my commutes. I'll run 93 when I know I want romp the car with some buddies or something alike. Also, I only use top tier gas stations. This site was recommended to me by a Ford rep:
Licensed Brands | Top Tier Gas

Going on 30K with no tune. Going to be getting my valves scoped after the winter to see the carbon build up. Hoping to not be disappointed.
 

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You can run 87 with no problems. The car is rated for 87 and there won't be any mpg difference. The ST engine is actually low compression (9.6:1 iirc) so octane needs when not on boost are not that high. The engine management won't have to pull timing, so you will get the same mpg as you would with mid-grade or premium.

It's mportant to understand that the weather - temperature in particular - affects octane requirements. The colder the weather, the less octane needed. Below fifty degrees, I can't tell the difference between regular and premium in my stock ST. During the hot summer months, there's a huge difference. On a humid 90 degree day the car falls on its face anytime you go above 5lbs of boost on regular. So if you want to be frugal and have some fun too, you can run regular much of the year and pop for premium only when needed.
 

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You can run 87 with no problems. The car is rated for 87 and there won't be any mpg difference. The ST engine is actually low compression (9.6:1 iirc) so octane needs when not on boost are not that high. The engine management won't have to pull timing, so you will get the same mpg as you would with mid-grade or premium.

It's mportant to understand that the weather - temperature in particular - affects octane requirements. The colder the weather, the less octane needed. Below fifty degrees, I can't tell the difference between regular and premium in my stock ST. During the hot summer months, there's a huge difference. On a humid 90 degree day the car falls on its face anytime you go above 5lbs of boost on regular. So if you want to be frugal and have some fun too, you can run regular much of the year and pop for premium only when needed.
I get 5-7 better MPG's on 93 over 87 octane.
 

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I am running 87 in the winter because 40 cent diff and I am in Upstate NY so snow. No need for more power. Once time hits for my Summer Tires it is back to 93.
Same thing I do...except its 60 cent diff in MI these days (I can remember when it was only 10). In the cold weather, I've noticed ZERO MPG difference. Not sure in the summer, since I only use 93 then.
 

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If i wasnt running a tune i'd probably be running 87. I felt no performance loss when stock, and the ecu will make timing adjustments to resolve any possible ping


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My Boost gauge only hits about 16psi with 87. May be cold temps and keeping boost lower to stay within the torque range. If the computer adjusts for that.
 

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The 8hp loss is only at the top of the RPM band. The ECU will detect knock and adjust accordingly for the octane you have in the car. No issues or concerns with running 87. And you should actually see better fuel economy running 87 over 93 since it burns hotter. You'll only notice if you're comparing similar driving habits in similar weather and temperature conditions. Only need to run higher than 87 is if you're tuned or want that extra. If you're commuting and not going into boost often, you can save the money and run 87.

At the same time, if you do the math you have to drive a pretty serious distance for the price difference to really net out to be significantly more. A friend of mine did the math (with a 50 mile one way commute) and he said it was less than $100 extra per year to run 93 so he said F it and runs 93 all year round now.


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