I have a 2005 S coupe and have been using 93 octane since new. Anyone have experience (good or bad) with less?

 

THats all I use because it is the only supreme gas sold in South Carolina. Plus I use Shell it's a top tier gasoline with the correct amount of cleaners as recommended by BMW.


Art

 

Where in heck can you get 93? Never seen it in CA.

 

you're car can use the octane.

Matt

ps, for more info search on "timing retard" and "octane". There's a bunch of info out there already.

 

Thats what is sold here by Amoco. Shell, Citgo and othere gas retailers,


Art

 

Don't have Amoco out here. I'm boycotting CITGO because it's owned by Hugo Chavez, and surprisingly, there's no Shell stations near me. Oh well.

 

Then how about Cheveron? look up toptier.com


Art

 

Well we can't get 93 because we live in Cal. Its another one of those great Tree Huger laws. So In cal 91 is the best you can do unless you want to buy 108 and mix it.

 

The octane that we have in the east is based on refining and the "need" that we have. Heat and humidity along with lower elevation are the factors. Even though parts of CA are lower elev., it's not near as humid. Therefore, the oil comps say that you all don't "need" it.

Correct me if i'm wrong, this is just how it was explained to me.

 

What is the big beef with 93 and CA??

 

Two whole octane points are worth a lot in the performance world.

 

I switched to mid-grade (89) almost 2 years ago and it has worked out fine.....no problems. I have a 2003 Cooper. I'm in OH and all seasons it has been ok. I'm from CA so I understand the gas issues you mention. Our gas prices fluctuates here on average twice a week....up 25 cents a gal..then down 10 cents then back up 15, etc etc. It is ridiculous. FYI to Gromit...there is a red with white top here locally with tag that says Grommit. Were you separated at birth? :-)

 

Chevron's high is 91, Same for Valero. I think ARCO has 92.

 

take those tree hugger laws comments and stuff them! Just look at a photo of the LA basin from 1972! "Tree hugger" laws are what mandated first the catalytic converter, then fuel injection on modern passenger cars. Without it, you'd be struggling to get 150 supercharged HP out of our cars while getting about 15 mpg. And you'd have to know how to tune Webber carbs, often.

CA is the only state in the nation that has a separate agreement with the fed gove that lets us set our own emissions laws (this is the source of the 49 state legal labels you see). Because of these laws, and the formulations used in CA, you're not going to find a lot of high octane gas here. You can find an occational 92 (will have ethanol) and some 100 (lots of tolulene or something).

Also remember, that octane isn't energy density, it's knock resistance. And I'm sure that the car will be fine on 89. It's got a sensor to retard timing. It would be interesting if a cooper driver logged a bunch of tanks for milage to see if it went down with lower octane gas. It sure does on the S. You can also log timing to look for retard. The mileage goes down the toilet when the timing is pulled.

Matt

 

yep luckily 93 in GA

 

In a physics class I had in college, we learned that ounce for ounce, regular gas releases more energy during combustion than premium.

 

And thus the need for higher octane in the appropriate applications.

Engines 101:

Higher compression --> more heat --> gas igniting at improper times during the cycle (other than at the top of the compression stroke, beginning the power stroke). This is ''knocking,' or 'pinging,' or 'detonation.' Bad for engine parts.

Higher octane fuel contains less energy so it will not ignite at any time other than when it is supposed to, given the proper application.

It always cracks me up when people say they use 'the good stuff' (super or preminum) in cars that do not call for it. They are paying more money for fuel that is less efficient for their needs.

Zip

 

O.O i think i use 93. i have no clue..i just know i have to get the most expensive one..lol
that's how i always look and say it as. used to the higher gas prices from my civic si anyways. xD

 

I think the highest I've seen is 104 in CA where I am, and only one gas station has it, and i think it's like 6 bucks a gallon... my firiend used to run it in his 2 stroke bike... just don't have the cash for half a tank of that stuff lol

 

Is that really the website you meant? That site's for a company that makes products that package boxes and stuff for pallets...

 

I assume this is the website in question...

 

They'll also be paying for a new catalytic converter and possibly an engine also. Premium fuel used in a lower compression engine does not burn efficiently, or completely. The deposits tend to want to cling to the valves as carbon, which is an excellent insulator. The valves can build up enough carbon, to prevent them from cooling off, and thus eventual burning or melt-down. And guess what all that unburnt hydrocarbon is doing to the CAT? Plugging it up.

 

back before fuel injection and knock sensors, you'd set the timing and that would be it. Now engines have knock sensors and can adjust timing on a per cylinder basis every ignition cycle (not all can, but the Mini does). What this means is that the car can take advantage of an agressive tune, without fear of damage from too low an octane.

As more and more cars come with knock sensor technology, the rated octane will be the octane at which they gaurantee a bunch of things, like power and accelleration times. But most will be able to use more octane than is "reccomended".

I'd also heard of one car that came out with a premium suggestion, and people complained as it wasn't a sports car, and it was "re-rated" to 89....

But as more and more cars come with computer control, they'll pretty much be able to take advantage of the extra octane you dump in the tank.

Matt

 

Still not sure if a computer controlled timing, will cause a better burn in the combustion chamber. It'll certainly control pre-ignition.

 

such that it can use a good grade of gas at good conditons, and it pulls timing from there. For most day to day driving, it never happens. When you floor it, it pretty much will no matter what on 91 on a MCS. Add mods and it can pull timing through the whole RPM band. So you will get benefits of more effective advance as the higher octane allows the car to run up to the programmed "best case" timing. I haven't done enough logging on enough cars to know just what this octane rating is, and how it changes with temp and humidity and the like. I'm guessing for most the car will improve up until 94 or 95. But this is just a guess.

So the old sayings will still be true, but with a much higher "premium" level being usable before there's no benefit to be had without hacking the ECU.

Matt