Jersey Monte

With the rising cost of gasoline(again) I read in my owners manual that 87 octane fuel can be used with a reduction of HP .
I have been running 87 in mine for about 4 months with no side effects
Haven't goten on it, but car runs surprisingly well getting about 24 mpg
average easy diving, I will probably go back to premium in the summer

kylerohde

Same - I don't notice a difference in the least. Guess I might if I was drag racing it but for normal day to day driving, I see no difference. I've kept very close track to see if the mileage is any worse with 87 and I haven't see a noticeable difference, and certainly not enough to make cover the additional $4 or so per tank it costs for 91 versus 87.

MyStang2010GB

For the difference in a tank of gas between 87 and 93 I just run the 93. Car isn't a daily driver anyways so a tank can last me a few weeks.

5LHO

I split the difference and run 91. Safe everywhere, max power when needed (yeah right on public roads in the winter).

TheReaper

I run 93 because we don't have 91 and will continue to do so because I need the 5 extra horsepower.

11SHELBYGT500

I think it's 10. lol

jskup1

For saving only $3 - $4 per tank, I wouldn't risk it. In my RX8 that required premium, running anything less caused detonation. Especially with ethanol being blended and the reports of incorrect octane ratings, you can't even really trust 87 truly being 87.

kylerohde

Since 91 is the highest octane available in many states, the car is optimized for 91 octane. Unless you can only get 93, you're wasting your money using it (of course, if you have been tuned for it, that's a different story.

Hard to argue with that, but I think this motor is infinitely more flexible than that rotary. I've run at least 20 tanks of 87 through mine with zero noticeable difference. Only real difference I've seen is when I was able to find pure gasoline. The car loves it.

2012GTCS

Hmmm wonder If they have pure gasoline around me. You got it at a station or a racing spot?

jimmbbo

To prevent detonation, the knock sensor system adjusts the timing in response to the fuel octane being used, resulting in a loss of ten HP at the top end.

87 octane is perfectly safe, and IMO is a painless way to save money, unless you just gotta have those last ten HP.

cinque35

if sunoco still had 85 i'ld use it.

the little gain isn't worth the big cost







.

kylerohde

Try buyrealgas.com and pure-gas.org - not a lot but still some spots out there.

MustangGTPilot

Shame they still put a little lead in aviation gas which is 100. Just back from Dubai and shocked that their "low quality" gas is 95 and regular is 98 octane!!!

2010MustangGT

Page 292 of your Owner's Manual

SD CALSPCL

I have always used Premium, since it is 100% pure gasoline, in the area where I live. Everything else has Ethanol added.

According to a fact sheet, from Ford, with Premium you have the full 412 hp, while Regular will drop that to 404 hp...not even noticeable in "normal" driving.

11SHELBYGT500

402 with regular

jimmbbo

Since ethanol can be used to increase octane rating... buying "premium" fuel does not guarantee you're getting "100% gasoline"...

"Octane rating does not relate to the energy content of the fuel... It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where the octane number is raised by blending in ethanol, energy content per volume is reduced."

The loss in maximum HP is due to the timing changes made by the knock sensing system to keep the fuel/air mixture from detonating...

11SHELBYGT500

If its a DD just use the lowest grade you can. You're not going to miss 10hp

MyStang2010GB

93 is more available where I live than 91 is. I actually ran 91 a few times and could hear pinging....so went back to my favorite station and the 93

11SHELBYGT500

What????