# Fuel Grade: Premium vs Regular



## 330ximd (Sep 20, 2005)

99flhr said:


> Repetitive person # 3 (330ximd) I believe Fast Bob made that abundantly clear way back in post #4. Then it was "seconded" in #`s 5,6, 8,9,10


Wow, you are a very smart person, good job with the observation. :yawn:


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## 99flhr (Apr 12, 2005)

330ximd said:


> Wow, you are a very smart person, good job with the observation. :yawn:


 I also observe that the person using the word repetitive has more posts in the thread than anyone else. :rofl:


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## 330ximd (Sep 20, 2005)

99flhr said:


> I also observe that the person using the word repetitive has more posts in the thread than anyone else. :rofl:


Wow, again, you are brilliant, uber-genius.


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## 99flhr (Apr 12, 2005)

330ximd said:


> Wow, again, you are brilliant, uber-genius.


 My, my, touchy aren`t we? and once again you`re REPEATING yourself!:rofl:


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## 330ximd (Sep 20, 2005)

99flhr said:


> My, my, touchy aren`t we? and once again you`re REPEATING yourself!:rofl:


Naa, not really. For someone focused on pointing out that people repeat themselves, you definitely are an amazing person. Give yourself a pat on the back, and tell your mom that you special. :thumbup:


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## 99flhr (Apr 12, 2005)

330ximd said:


> For someone focused on pointing out that people repeat themselves,


 Helllooo! do #`s 17 & 18 ring a bell? I merely used the same term that you did and now your knickers are in a knot. I apologise.


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## akhbhaat (Apr 29, 2003)

Those articles were written with the average idiot in mind. There's no need to fill up paragraph after paragraph with random anecdotes or quotes by "experts" or other absolute rubbish - if people could simply be educated on the topic, such articles wouldn't even need to be written. Of course, if most people could be educated about _anything_, many of the world's most pressing problems would cease to be - but I digress.

Octane rating measures a fuel's resistance to detonation. The increased cylinder pressure of a high compression engine demands fuel which is less volatile (i.e. prone to spontaneous combustion) for safe operation at maximum efficiency. Using an overly volatile fuel in a particular engine can and will result in premature, spontaneous detonation (knock), which can damage or destroy the engine. The idiot-proof engineering solution implemented by most manufacturers (because they know most of their customers are idiots and will likely at some point use the improper grade of fuel - or because some will be unfortunate enough to be unable to acquire high octane fuel in a pinch) is a knock sensor - essentially a device which is designed to adjust ignition timings in the event that a lesser grade of gasoline is detected. The obvious consequence is a decrease in the efficiency of the combustion process, resulting in loss of power and/or fuel economy. Note that if there were nothing to be gained by mapping the engine's default ignition timings around higher octane fuel, then the manufacturer wouldn't do it. As it is, increasing the compression ratio is one way to improve power output without an increase in displacement.

By the way - I shouldn't need to illustrate what will happen if you're using lower grade fuel and the knock sensor fails or isn't operating properly for whatever reason.

The bottom line: RTFM! If your owner's manual recommends 91+ octane fuel, *it does so for a reason*. Likewise, if you're putting high grade into an engine designed and rated for 87, you're just wasting your money (unless you really believe that the extra detergents advertised by many of the larger oil companies are actually worth the added 20c per gallon on their own).


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## 650iOzBoy (Sep 2, 2005)

I use sunflower cooking oil for my 6er. Runs like a dream.


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## ProRail (May 31, 2006)

650iOzBoy said:


> I use sunflower cooking oil for my 6er. Runs like a dream.


Yeah. It may cost more but think what you're saving on taxes.


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## mikevaquez (Jun 23, 2006)

I use 93 Octane all the time have never put anything lower then that. The car runs good and haven't had hany major problems. I have 42xxx miles on it and it's an 04 325ci


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## ryip (Sep 20, 2006)

For vechicles that recommend premium gas, I'm sure 99% of the people who lease their vechicle and have no plans to purchase the car at end of lease put regular in their cars.


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## 650iOzBoy (Sep 2, 2005)

ProRail said:


> Yeah. It may cost more but think what you're saving on taxes.


Plus when the engine burns the sunflower oil, there's a beautiful aroma that comes with it too. Scent plus performance. Who needs the 98RON sh!t. :tsk:


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