Even the tv commercial says Hp number obtained with premium fuel...

 

lol, so after I read all these post, I went out and pulled my manual out of my 11. I'm going to type word for word what it says on page 290 out of my manual for the 2011 5.0.

Octane recommendations (5.0L V8 Engine)
"Your vehicle will run normally on 87 octane regular fuel without damage to your engine, but premium fuel with an octane rating of 91 (R+M)/2 or higher is recommended for best overall performance."

Take it for what it's worth, but I will run 91 octane in my car with a 11:1 compression ratio. Dyno's also show an increase in HP when using 91 as opposed to 87. These Copperhead ECU's in these cars are not like other cars. The Copperhead will actually increase or decrease the amount of timing based on what fuel you are running.

 

During hot summer where detonation is more imminent I would recommend 93 or higher. You have to understand how octane work in relation to combustion and everything else that are associated with it such as ecm, timing, knock, etc... With my investment I want the best and everything I can get out of it. If you can afford a $30k+ 412 or 420hp vehicle you can or you should put in what is recommended by the vehicle mfg. Just my opinion.

 

I didn't spend over 30,000 dollars on a car to cheap out on fuel ,its a hi performance motor put the good stuff in it for crying out loud and if u spent 35-40 K on a car and whine about fuel costs then you really couldn't afford it in the first place

 

Plus 100 LOL!

 

You got me thinking as I have been using 87 only. Where I live there is a 30 cent delta between 87 and 93. I put 8000 miles/year on my GT. I get around 17 mpg around town. Thats 470 gallons/year. At 30 cents extra/gallon, that comes out to an extra $141/year. Not as much as I thought, or about $3.90/fillup as it usally never takes more than 13 gallons. Balance that out against any mpg improvement, and the $141 goes down.

Joe C

 

This weekend I gotta reread my manuel to see if it's different.

Stay tuned

 

lol
Ford actually contradicts themselves because on the previous page it says 87 octane is the recommended fuel. Turn the page and ford recommends you run 91+ octane for the best performance.

 

Not contradicting at all.....87 recommended but 91 gives best performance. That info tells grandma she can run the cheap stuff and be cool in the Mustang....and grandpa can squeeze out the extra when she lets him drive it.

 

Well if grandpa is mixing 91 with 87 he's getting 89 so he better get 93 if its available.

 

2012 GT here. I assume that when i drove the car
from dealer that premium fuel was in the tank. After a couple of fill ups using premium fuel I decided to try 87 octane. I noticed less torque or pull from regular driving and acceleration. I have no numbers to support this and maybe it was just my mind expecting less performance on 87 octane. But it was enough to convince me to return to premium on next fill up. This was during first two weeks with the car with around 500 miles. I havent gone to 87 since. But now i want to experiment with using 87 and see if if there's noticeable feel of decrease in performance...

 

I run 93 just annoy people on the internets.

Also i accelerate slowly to activate the skip shift.

 

Update... I have owned the ' 12 5.0 6MT since March, have 7 K miles. Most of the time I used 93 Octane premium, especially during the summer months. When gas went up to $4/gal I figured I run a few tanks of regular through it. The owners manual does recommend regular. I noticed a big difference. I would characterize it as this, the once wild stang became lethargic. Pinging, no...but lugging in higher gears and generally not responsive as it once was. I ran about 3 tanks of regular but now I'mback to 93 octane, WOW, it's a huge difference. I have other cars that the owners manual says, use premium for increased performance, and I have tried both fuel types and could hardly notice a difference. But the 5.0 different story... The beast loves premium.

 

I run 92 octane VP racing fuel, it's ethanol free and is an amazing fuel. I've only had regular in it when the dealer filled it up, otherwise it was 91 at first, then 92 vp.

 

For the past 3 months I have run nothing but shell 93, gotta say I can tell a difference on the butt dyno, and I don't have any issues with running rough like I have with other fuels, my avg mpgs have gone up also

 

I have been running 93 since day one. More smiles per mile IMO.

 

I ran regular for a bit when the prices where high, now I'm back to 93.

 

You guys are amazing. LOL

 

After reading this thread, I noticed the majority of the comments centered around HP. Don't forget, the difference between Regular and Premium is the additive package put in by the oil company. Each company has there own idea of what is good. Premium has a more comprehensive package. I always use a Tier 1 gasoline, in my case, Conoco Premium. At the station I use, the Premium is alcohol free, pure gasoline. I noticed a big difference in my gas mileage when I used Regular or even Mid-Grade, both of which contain Ethanol. At my last check, after a drive, I noted a 24.6 mpg on Premium, mixed drive, Interstate (75 mph) and hills with lots of curves requiring shifting. So, the choice is a personal one, but don't forget your MPG when looking at Regular vs. Premium.

And, the EPA has approved upping the Ethanol content to 15% from the current 10%. I am not sure when we will start seeing this in the marketpalce.

 

that's a sad sad approval....