I just bought a 2004 and see that it uses premium gas. I have done many things to many engines and I want to know if there is a way around the premium gas. Is there a computer change that can be made? I can't imagine it has that much compression to warrant premium gas, could be wrong though.

Thanks,
Jim

 

I know several members put in regular gas with no problems... but I don't really know why. You bought such a nice car but can't afford an extra ~ $3.00 at the pump to fill it up?

 

I was thinking the Same thing...

 

Hey Pizzle,

I understand why you ask. I have an SRT-6 and have never put anything other than premium fuel in her belly, however, if I had a Base or Limited model, I'd consider it. You should be able to test a tank of regular or mid-grade and see how your car handles it. Your driving habits could come into play as well.

I'm always one who asks as customers, do we really know what we're pumping into our tanks.(?) I remember a local station getting shutdown because the tanks contained the same grade of fuel. Can you imagine the amount of money they made on customers blindly pumping "premium" fuel into their vehicles?

Another thing that gets me is the octanes of fuels used in Europe. I remember being stationed in Germany years ago and the lowest rated fuel there was higher than our premium in the states! You could get 95 or 98. My 1999 Honda handled it well, but my Explorer didn't like the fuel at all. Maybe it was because it was a Ford, but I have to mention it anyway. Is there are difference in the equation used to calculate the octane rating for the European market? Somebody?

Anyway, I say give it a shot. If it works, stick with me...but don't go back and forth between the different octanes.

 

Hello all,
New to the forum...happy to be a xfire owner...always wanted one...and yes now I'm a clean freak when it comes to the vehicle....

On topic...I moved onto the xfire after owning a Mercedes...which took premium gas...since I enjoy keeping tabs on the tech aspects of my cars I was a member of mercedesshop forum and this question was a common one...MB engines have knock sensors and other electronics to compensate for lower octane fuel so as to avoid damaging your engine...this also usually ends up decreasing performance (albeit usually unnoticeable) as well as lowering your fuel economy a bit...which often negates any savings you may have incurred...

 

Welcome to the forum.

 

This has been mentioned before on the forum. It appears your answer is spot on. So if you just want the looks and are not that concerned with performance, regular should work fine.

Unless the difference gets huge (around a dollar a gallon) I will stick with premium. While I don't hot rod all the time, every so often (quite often) the little beastly lets me know it would like to sprint. I can't help it, I just have to respond with a gentle jab to the throttle. I have never owned a vehicle that felt so integrated with the driver and gives such an overall wonderfully effortless performance driving experience.

 

Yes there is. I don't recall the specifics but a Google search will bring it up for you I'm sure. I also seem to recall that, although the calculations and ratings are different the Euro gas still ends up being a point or so higher than what we get here.

As for which fuel to use - if the manufacturer states premium then I use premium. Using anything lower has the potential for reduced performance and possible pre-ignition. One is less fun, the other is just not a good thing. On the other hand, if the manufacturer recommends regular there is nothing to be gained by using a higher octane, unless you detect pre-ignition.

Oh, and when I filled up the other day I paid $38.18 for 12.645 gallons: $3.019/gallon. I had filled with regular at the same station for the $2.859 price I would have paid $36.15 for the same 12.645 gallons. I will gladly spend the extra $2.03 to prevent a loss of performance and the potential damage from pre-ignition. I'm sure most, if not all, of us collect that much loose change through the course of a week anyway.

 

I've checked a couple sources and the static compression ratio is listed at 10.0 to 1. That would indicate probably at least 90-91 octane fuel. Now M-Benz does use a really sensitive knock sensor to prevent engine damage but once the timing gets pulled you're gonna loose power and economy. So while you won't hurt anything using regular there won't be much money saving if the MPG drops off. You could always test the effect by filling up with regular on the outbound leg of a trip and using hi-test on the return.
Keep the cruise on and see if there is any difference in MPG. I'm willing to bet the premium fuel improves the efficiency enough to offset the additional cost...

Slim

 

just skip the $3 coffee once a week. kinda funny that people will pay $5 bucks for a beer or something else but want to save money on gas for a $30,000 vehicle which they will have for years.

 

Premium gas around here is 10c a liter over regular, 35c per gallon, $5 bucks US$ on a fill. Gee maybe I will run down to Mt St Helens on the 26th just to save some money.

 

You can run lower octane fuel in this car, but you will sacrifice performance and possibly the longevity of the engine... These cars have a dual plug cylinder that burn very hot and are prone to pre-ignition because the engine was designed to limit hydrocarbon emissions by igniting every "atom" of fuel introduced. They also have very sensitive knock sensors which work in harmony with the 02 sensors and ECU that adjust the fueling and timing of the engine...

If you introduce lower octane fuel, it will promote pre-ignition (knock)... Then the knock sensor will retard the timing of the engine and reduce the fuel trim to compensate for the pre-ignition... Thus you have just been robbed of HP to make sure the engine doesn't explode itself...

So, if you like your car...

 

The $2 or $3 bucks saved by using regular VS premium will be offset by economy so why use it if you don't save anything?

 

I'm surprised that nobody has mentioned that the cheaper gas will poison the catalytic converters much faster...I'm not sure how much they cost...But I bet they ain't cheap!

 

It has nothing to do with the catalytic converter. It's all about preventing pre-ignition (knock). Here's a good source of info in case you're interested...

http://en.wikipedia.org/wiki/Octane_rating

 

Ditto, I like the way your mind works.

 

if you are very casual just use regular but people like me that can feel everything in the car, we gotta have premium.

 

This same question regularly comes up over on the V-Twin Forum. (My other ride is a Dyna Wide Glide). One issue that concerns bikers more than four-wheelers is that regular burns hotter than premium. In other words, my DWG on regular will shed more heat against my legs. I suspect that heat is also one reason why an engine designed for premium will not last as long on regular. However... the consensus among bikers is that you can safety run regular in the cold months and use the premium only when it's warm out with no impact on performance.

I realize that this does not consider the more-knowledgeable-than-I xF folks who have chipped in regarding the engine design and computer issues associated with burning regular. I just thought I'd bring this up for those who do want to consider regular. Me, I usually burn premium but occasionally I might pump regular or mid. Like Harleys, the xF is, I believe, designed for 91 octane and since all premium around here is 93, you can blend some lower octane in and still have fuel that meets the design specs.

Guy

 

Actually...when your computer has to play with the timing and/or fuel curves, you have more instances of a less than ideal burn in the cylinder. This increases hydrocarbons and oxides of nitrogen, as well as others...both things that the catalytic converter tries to remove from the exhaust.

This info came from a senior specialist of vehicle emissions and regulatory affairs at DCX, not a wiki.

 

Apkano, point taken. Those things will happen if you use the wrong fuel since the ECU will always sacrifice environmental friendliness to prevent the engine from turning into a grenade.

What I was trying to say was that the reason the Crossfire requires 91+ Octane gas is to prevent detonation because of its relatively high compression.