what would happen if i filled my xfire up with the premium gas sometimes and then used the plus gas sometimes? plus is the middle one? is this safe? with huge gas prices my parents are freaking about $30 a fill up.

 

with the 2 dollars you save you'll end up replacing those catalytic converters and paying more like 1800 down the road, here's a tip, get a job and pay for your own gas.

 

big dittos!!! yeah gas is the cheapest part or ownership! cheap gas means less mpg and remember 20 cents or 10% = about 2 miles per gallon to save gas don't speed!

 

and don't use the heated seats.

 

^^^ lol ^^^

Classic...

 

$30 for a full tank, try living in the UK more like $80 over here!

 

When I was over seas in Australia a tank of petrol was nearly $70 American. Just be glad we don't have to pay $2 per LITER!

 

At 55 are you still living at home, driving your parents car, using their insurance and getting them to pay for your fuel?

Get a life.

In reply to your question get the regular and give your parents the $2 change to put in your savings account for when you get older.

 

i'm 16 not 55.

 

It says your age is 55 on your post info (top right hand corner of your post).....or is that your dads age?


Join Date: Apr 2005
Age: 55
Posts: 15

 

in all seriousness why are we even bothering with this kid? here's what we do....viper2k0, buy whatever fuel you want, premium is what the engine is built for, but hey not listening to the manufacturers suggestions is the cool thing to do. run regular and tell us how fast you turn your car into a pile of sh*t. i put my money on 3 years. anyone care to wager with me?

 

To kinda get this thread back on topic, here is a little pet peeve of mine with regards to fuel.

If the minimum octane rating for the Crossfire is 91, why can't I buy it 91 octane anywhere?
Around here all that's available is 87, 89, 93, 94. Isn't 93 and 94 overkill?

And what car requires 89 octane? I've never come across one.

I'll continue to buy 93 octane of course (buying premium gas costs only about $3 more per tank).

I just thought I'd give my little rant.

 

This post is pretty funny but if you REALLY gotta save that extra couple cents, try this. Fill up with premium and then, when the car gets around 1/2 tank, put in 89. This way, the "median" octane rating would be 91 which I believe is what most cars that call for premium need to operate correctly. Your welcome.

 

Fill your tank with half 93 and half 89 = 182 divided by two equals 91! It's my understanding that most stations actually create their 89 (Plus) by mixing the correct ratio of 93 & 89. I'm no expert, but can't using too high of an octane also cause problems? The octane number doesn't necessarily mean that it's "better", just that it's formulated to burn at a higher temperature.

 

Close, the function of the octane rating is to indicate the temperature and pressure environment at which the fuel will ignite. Higher compression, or "coked up" engines require a higher octane content to prevent pre-ignition. Pre-ignition is the so called "ping" or "knock" that people can often hear when the fuel-air mixture ignites before the spark plug fires. Over time, a severe pre-ignition problem will cause the piston pin bearings and connecting rod bearings to wear.

Most modern engines, the xfire included, have knock sensors that will detect this pre-ignition and retard the timing to allow operation with lower octane fuels. However, this should only be trusted in an emergency situation where the lower octane fuel is all that is available. Even with the engine trying to watch out for itself, if the octane is sufficiently low it cannot compensate.

The "premium" designation was added as real octane is produced in lower quantities in most refining processes and hence the oil companies could charge a premium price for the rarer component. For many years, the anti-knock properties of octane were obtained by adding tetra-ethyl lead to gas until the catalytic converter, which is chemically fouled by the lead, came into widespread use. Now, ethanol is often added, as it also causes the octane number to be increased. Both octane and ethanol actually decrease the energy content per liter of fuel.

Actually, the amazing part is I can still remember these discussions from the chemistry class I took way to long ago.

 

Thanks for the insight Rick,

I'm starting to think there is a conspiracy to why 91 octane isn't sold. And yes you can make fun of me and call me cheap for suggesting this, but is there any car with that requires 93 or 94 octane?

I'm just saying 5 cents more per gallon for everyone that buys premium gas adds up to billions of dollars per year.

----

Exxon Mobil, the world's biggest oil company, has announced record fourth-quarter profits of $5.12 billion compared with $2.7 billion the previous year. The US oil giant attributes the huge growth in profits to soaring oil and gas prices. And full-year profits climbed to $17 billion, hitting a world record.

----

http://news.bbc.co.uk/1/hi/business/1134616.stm

 

RickB, brilliant memory! I nearly was on the way down to the cellar to find my old chemistry scripts. Which aren't that long way back ...
Here in western Europe you even don't find gas lower than 95 octane. Before I go to high speed drives I always fill up with 98 octane. Just to be on the safe side.

 

So could 93 octane actually do more harm than it does better for the xfire?

 

Not really. It allows for a controlled flame front in the cylinder. With the twin spark plugs, the computer can "shape" the burn to get a smooth pressure wave in the burning gas rather than the random pressure pulses that pre-ignition can cause (the flame front starts at random locations in the compressed volume).

Of course the worse case I've seen was with an old Honda 50 scooter I had in high school. The compression was in the 12+ to 1 range, requiring very high octane. I once put a tank of regular in it - the only way to shut off the engine was to turn off the fuel ****. I ended up draining most of the tank.

So the higher octane doesn't hurt, except in the pocketbook. It may be required as cars get older and more deposits form in the combustion chambers, as these may form sites where pre-ignition occurs. My old conquest required higher octane with the turbo. Just as bolting a turbo or super charger on the standard xfire would require a higer octane due to the higher pressures in the cylinder.

On the far end of the scale, think diesel - the ultimate high octane fuel. The diesel is efficient due to its extreme compression ratios, but it needs a fuel that doesn't fire easily to keep from blowing the engine apart.

And yes, at one point in my checkered career as an engineer, I was designing car components. I was on one of the teams developing the first generation catalytic converters.

 

In general, if you use a lower Octane fuel, then you will possibly encounter detonation or "Knock", especially on warm days. The engine has a knock sensor, which is a kind of microphone that listens for knock in the engine. If the sensor hears knock it will retard your timing advance and to eliminate the knock and as a result your performance will suffer during acceleration.

If your knock sensor does not hear the knocking then you can fairly quickly trash your engines moving parts, especially the cylinders and rings as the detonation occurs well before top dead center is achieved, on the compression stroke. I have seen holes in pistons the size of quarters caused by knock erosion and detonation. Not good.