It's been a week since I drove my 2013 GT off the lot. The salesman that sold me the car filled it up with regular gas, 87 octane. He said he has a 2012 GT and runs regular with no problems. I've been driving it for a week now and it sounds great, no knocks or anything. But I'm down to a quarter tank and I'll be filling it up soon. I know the book says (recommend premium gas) but if I keep it at 87 octane, will I have any problems in the future? Thanks.

 

No problems unless you just don't really want all the HP your motor can produce. Otherwise keep putting regular in and save that $10 difference a month and don't have as much fun.

 

Welcome to the forum and congrats on your car! This is probably the most-discussed topic in this forum and by searching, you'll find hundreds of comments about it.

 

Dude! If I have much more fun than I'm having now, I'm going to get a ticket. So i'm losing 10hp running 87 octane right? Anyway, it has less than 200 miles on her. Right now i'm taking it easy.

 

I think it's the kind of question each person has to answer for themselves. It's like boxers or briefs? There is no right answer. Either way, you're in a Mustang. That's a win in my book. Unlike boxers, I hate dangling around.

 

He's right. Your computer adjusts to the octane in your tank. It won't hurt it at all and even Porsche's and corvettes run fine on 87 pump gas.

 

I ran 87 in mine for a few months before switching to 93 out of curiosity more than anything else. It's probably my imagination, but it seems to run smoother, and I swear it's a little quieter than before. Fuel economy also went up a bit (maybe 1.5 mpg).

 

You won't see the full benefit of 93 without a tune though. -insert product placement here-

 

The owners manual says use premium, its tuned to run premium not regular. Why would you buy a performance car then cheap out and buy reg fuel? 11.1 comp ratio doesnt like regular fuel.

 

The only time you would have a issue with using 87 octane fuel is if you were using a performance tuner and running a 89 or higher octane tune. Thats not good but since you don't have a performance tuner, run what ever octane grade you want. Your paying for it.

 

20 years ago the $0.25 between regular and premium was a big deal, as regular was $1.10 and premium was $1.35. Now, with regular being around $3.70 and premium being $4.00, it's a no-brainer to always run premium in cars like these that actually benefit from the better gas. You're not really saving much going with regular compared to the cost to fill the tank.

 

I always run the highest octane level possible in the cars I "enjoy."

 

Well, that's not exactly what the 2012 owner's manual says:

Octane recommendations (5.0L V8 engine)Regular unleaded gasoline with a pump (R+M)/2 octane rating of 87 is

recommended. Some stations offer fuels posted as

Regular with an

octane rating below 87, particularly in high altitude areas. Fuels with

octane levels below 87 are not recommended. Premium fuel will provide

improved performance and is recommended for severe duty usage such

as trailer tow.

For Shelby GT500 octane requirements, see the

Shelby GT500

Supplement.

 

On my 13 inside the fuel door it says premium, but it doesnt matter. I know better and will run premium. Every vehicle I own requires premium, both of my bikes,even my V10 Superduty. Keep running reg fuel and wait and see what it does to cast pistons.

 

The car will produce less power with 87 octane regardless of what the manual says is recommended. For the extra $4 a tank ( and the full 420 horses ) gimme the premium!

 

I have to run premium because I have an SCT tune added. the lower octane would make it run crappy. But you are correct the mustang was designed to run on all grades.

 

My 13 Gt book says 87 octane. Thats all I have run. I get 24 mpg on the highway at 79mph.

 

See what you started OP, jk. All the info does say for the full 420 HP gotta have premium. Mine has only had at least 91 since day one.

 

I've ways run premium fuel

 

I'm with the majority here, run premium and call it a day. I have a 93 tune Steeda cold air and run 94 gas in it. It runs like a champ.