Octane question (for the octane savvy)

Ok folks I am sure this one has been beaten into the ground many times. However, I am now on a quest. Sort of. A friend of mine had an interesting
view to share on the topic of 87 octane vs 91 octane (low vs high) Below is his response to my statement (which is below his). For the record, he has a Nissan Sentra, Spec-v, his wife has a Dodge Noen (both run 91) I have a Dodge Dakota, and the bike I was referring to in my post was my old Suzuki SV650s. (I run 87 in both, as per their owner's manuals)
I know there are a few guys here that work for the oil companies. Do you happen to know where I might find, in writing, on a fuel company's web site that states that the only difference is the octane rating, and NOT the detergents? (or proof stating otherwise) I will be researching as best I can during the weekend, but any direction would be appreciated.
------------------------------------------------ Yes, i've read some very very extensive articles on gasoline octane. Here's a few notes:
- 91 will always run better than 87. - 91 from the different gas companies is all DRASTICALLY different - Running 91 on a car that doesn't need it WILL NOT damage the car. It will make it run just the same as what the car is tuned for, but it will allow an extra margin of safety from unpleasant car conditions (i.e. heat soaked radiator causing overheating, creating knock conditions, 91 will not require the ECU to compensate nearly as much or as early as if it was on 87) - 91 octane at most gas stations will contain extra detergents and cleaners which will prevent your injectors from clogging up as easy, keep the valves cleaner, and keep all related fuel lines/pump cleaner and free of debris. - 91 octane at 76 or Shell is considered the absolute cream of the crop for Southern California. The difference between these two and Cheveron/Exxon/Mobil/Generic brand is HUGE. Some stock cars are noticing a 5-15% power drop from just using the wrong brand of 91 octane. - For reference, your air conditioner will sap around 10% of your cars horsepower when turned on. - Also for the record, if you do the math with a 10-11 gallon fillup, thats only an extra $2 each time you fill up (1-2 times a week means an extra $8-$16 a month) for a cleaner engine and safer driving condition. Thats worth the extra cost in my book.
----------------- Original Message ----------------- From: Trey Date: Jun 3, 2005 4:18 PM
Have you actually read up on what makes 91, 91? or what the three grades do? If the car is not designed for it, the higher grade can actually damage teh car. My truck for example, it notes not to run 91. 91 can degrade performance in a car designed for 87. Some cars (like your spec-v) spec that it will run on 87, but to use 89 for best performance. In that case, the car WILL run on 87, but the knock sensor will retard the timing (reducing power) to keep it from knocking. and is able to advance the timing with the 89. I remember my motorcycle actually felt down on power when I ran 91, it actually ran better on 87. as for being "negligibly more expensive than 87" its about a .$20/gallon difference. Doesnt sound like much, but when your buying 20 gallons at a time, and get 12 MPG, it adds up VERY fast. Thats an extra $200 a year Im just blowing out the tailpipe of the truck.
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Calif has SHIT for gasoline....they have "watered" it down with low power petrochemicals to make it "burn" cleaner, but, in doing so, has reduced the amount of power that can be produced from it.
Less power=less mpg....Out of state gasoline gets 20% better milage than the shit they sell us here, but most people won't even realize this until they drive outside Calif...
RISE UP AND REVOLT!
MORE POWER to the MASSES
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Your "friend" has a lot to learn. The oil companies just love people like him.
If 91 was always better than 87, the oil companies would promote it that way. They don't, because it isn't. I especially liked the comment about the A/C sapping 10% of your horsepower. Since most modern compressors draw 3 to 5 hp, his statement would be true if you were driving, say, a '71 aircooled VW which had 50 hp. More hp = lower %. H
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