I guess it all depends on why you bought your crossfire. If you plan on driving it like a Buick, and want to get off as cheaply as possible, use the 87 octane stuff but then you probably never should have bought a sports car in the first place.
The car is designed to provide higher performance by taking advantage of higher octane gas.

 

I'm really amazed by the number of people using regular. Of course if all are leased cars, then it would make sense. I also don't like to make the big oil companies richer or know that my hard earned money is going to the middle east...However, I knew when I purchased my car that in order to get the best performance I would have to use premium fuel... So be it, an extra few bucks at the pump... I would also think that a few more $$$ at each fill-up wouldn't be an issue for most current owners...Now for second and third owners thats a different story...

I also noticed that some have claimed to have used nothing but regular and haven't noticed any difference in performance...I suppose these opinions are based on seat of the pants feelings after occasionally running with a refill of premium mixed on top of the regular...then putting regular back on top of the previous mix...No wonder they haven't noticed any difference.

Now this tops it all IMO,
Why spend hundreds of $$$ on the "spring booster" a gadget that doesn't add one bit of performance and not use premium??? I guess I don't get it and I'm not going to make many friends by opening this can of worms... Sorry, but thats the way I see it...

By the way, let it be known that the spring booster is going to do wonders for your fuel economy. Also, your slow speed drivability (Traffic and parking) is going to be a wonderful experience. The only thing this gadget does is change the progressively ot the throttle plate opening, Its going to make it non linear (Big opening of the throttle plate for less travel of the gas pedal).

With what I'm saving by not jumping on the spring booster bandwagon is going to buy me a few tanks of premium and I can still use my right foot as it was intended to put the pedal to the metal...

 

Well, if I've learned anything from this thread, it's not to buy any "previously" owned Crossfires in the future.

 

Well, if you want to spend your money on 91 knock yourselves out. I drive a coupe and while it handles well, I don't consider it a "High Performance" car. At 215 hp it has some 50 less hp then my wife’s Accord. I bought it because I love its looks and it reminds me of a 1967 Charger. In the past I've owned Corvettes which I do consider "High Performance" so I do know the definition.

 

WOW a 265 hp Accord!!!
I guess you consider your wife's Accord a "high performance" car...compared to the XF...

 

Read my post again. Just using it for comparison. I'm saying that neither of them are. If my X-Fire was an SRT it would be a high performance car, but at 215 hp it's not. An SRT with 330 hp and 13 sec quarter miles, meets the definition of a high performance car...

 

Wow...pretty tuff crowd to please.
I suppose we all have our own definition of what constitutes a "high performance" car.
But even though I have a car that's capable of breaking into the 11's if provoked by a really excellent driver, (not me) I still consider my Crossfire (that's supposed to run in the high 14's) a high performance automobile.
Just my $.02.

 

+fireamx, do you have an AMX and if so what year? Those were nice looking cars and quick too.

 

You all don't understand engines do you! Ok lets look at a Lotus Elise, it is sub 200 HP but it requires high Octane, HIGH COMPRESSION ENGINE. Similar to the Crossfire, it is Chemistry and Vapor Pressure not performance. We have a 10:1 compression engine use lower octane and you are running a retarded timed engine, and lower HP. So here is what I have to say go ahead and run regular if you are wanting to drive a retarded timed car go for it. I don't care and many others probably don't. I would classify you as a dumb tight wad.

 

Napasanaoma is correct; what little saving you'll notice at the pump will be lost in efficiency. Considering our car gets low 30's on the interstate, well it does when my wife drives it, or mid to high 20's when I drive it and the tank only holds 18.8 gallons, the savings for me between 85 and 93 would be less then $6.00 a tank. Compare that to my Cummins at 17 mpg it's chump change. If you concerned about saving $6.00 on a tank when you probably only fill up twice a month then maybe a Chevy Cobalt would be a wiser choice. They are available for less then $10K and can run E85.

 

Jeeze guys, settle down... I do understand engines and there was a time I understood octane ratings...but one thing I do know is how to converse with other people in a civil manner. To Idaho, I wasn't talking about E85 (crap) nor was I talking about 93 octane fuel. We were discussing 87 vs. 91. And yes it will require the engine timing to retard, but I don't care. And I doubt there is that much delta in efficiency (does anybody here know). I hardly ever drive over the speed limit nor do I flog my car, period. (Yes, I could have bought Cobalt but I bought Crossfire…free country and all) I use it just like I would a daily driver because that's what it is, a very handsome daily driver. Now, since I paid for it and the know-it-all wine guy didn’t, I'm gonna run 87 octane in my car until I feel the need to take it over to the race track.
Know-it-all wine guy: you sound like a socially retarded engineer. I know this because I’ve worked with a few. You need to take it easy on the sauce when writing these replies because you come across as know-it-all a$$. You don’t know me and this isn’t the forum for writing an engineering dissertation, so I won’t…if I even could anymore. Try keeping your unsolicited personal opinions to yourself. The anonymity provided by the internet seems to bring out the a$$ in people like you.

 

Dude, I think YOU are the one that needs to chill...

...as for the octane issue, use whatever you want and don't forget to use 10W/30 oil (you can save a few pennies in that department too). Me, I'll stick with 91 octane and Mobil 1 0W/40.

 

Yeah, too much coffee...but now you've opened up another can of worms with oil.

 

OK, let me just say I'm not an engineer or scientist right up front. I base most of my automotive knowledge on past experience I've had with cars that I've owned. (and I've owned a few). Now I know thanks to computers that we rely on for almost everything these days can safely operate an engine management system. But I think the computers can only be expected to do so much. I mean they can't turn water into wine, or in this case, low octane fuel into high test. There is always going to be that high compressing ratio to consider, and be dealt with. No matter how much the timing is retarded by the computer, the actual space between the piston and the combustion chamber isn't going to change, and the "need" for higher octane still exists. The actual preignition is still occurring to some degree, just not to the point where you can hear it.
It's my understanding, that low octane fuel will ignite quicker, and burn hotter than a higher grade. I think that's one of the reasons it causes the pin holes in the piston and carbon that JMPIQUET spoke about. Eventually, somewhere down the line causing catastrophic engine failure in the form of holes in the pistons.
When a dealer tells you it's OK to use lo octane in your lease car, essentially they are saying, It won't happen to you so don't worry about it. But down the road, after we wholesale your car to another dealer, some poor schmuck is going to have to deal with the eventual problems it will cause. The dealers just look at that as "job security".
I'm not going to tell anybody what to use in their own car, all I can do is recommend something. If you're satisfied with the performance of your car while using lo test gas, then good for you, and God bless ya.
Personally, I have higher expectations from my car, so I feed it the best and expect the best in return. I also didn't lease my car, and assuming my feelings don't change for it, I plan on keeping it for awhile. So I really do not want to be instrumental in it's premature destruction.
I keep pretty good records of my cars, and when it comes time to finally sell it to another buyer, I'll be able to show them receipts for frequent oil changes, and gas records showing I always used the best.
Assuming this web site keeps going, and more threads like this one get posted, I would guess that future "used" Crossfire buyers will check in to see what to look for when buying a previously owned XF, and what to avoid.

 

+fireamx, I agree! It all comes down to how you treat your car if you plan on keeping it for the long haul.
I've tried regular gas and haven't noticed performance problems but...
I keep an eye on the tail pipes and find that the lower octane fuel does not burn as clean and I don't get as good MPG's. I'll stick with 91 to 93 octane for my own peace of mind. I think the better MPG's tells the story on how efficiently the engine is running. Last fill up I got 28.2 MPG. I only use Marathon or Shell gasoline here in Ohio. Fortunately the Marathon station has "Super Thursday" when they charge the 91 Octane price for 93 Octane fuel. YEAH BABY...

 

Hell, I just put a good German beer in her and away we go!

 

Ok, I am impressed. I think there is more intelligent people out there. By the response to our e-mails. I can read the hypercritic of A$$. At least I know the level of your intelligence. I understand vapor pressure and octane and compression. I understand what effects it has on a long term basis, I do not consider myself a A$$ as you have defined me.

I find a great appreciation for the hand creating a fine wine, this does not mean I am a drunk. Look if you want to drink cheap wine or bargain beer and burn low Octane gas in a High octane engine this is your privilege and I personally do not care. It just shows your basic knowledge of engine technology and your understanding of fine wine is less than your IQ!