which octane ?

Save your money. Unless you're at high altitude 87 should be fine. If it pings on 87 at low altitude the car needs repair, not high octane. (A Prius engine will often sound as if it's running-on or dieseling for a few moments after it shuts off. Be careful not to confuse that with pinging or knock. It does this when needed to burn off all remaining fuel to prevent hydrocarbon emission; it does not indicate a problem with the engine or the fuel.)

 

None of that is true. The car doesn't "remember" anything. It's a mechanical machine. The computer adjusts automatically to conditions.

The owner's manual specifies 87 "or higher", which means that 87 is fine.

 

<div class='quotetop'>QUOTE(adam1991 @ Mar 28 2007, 07:05 AM) [snapback]413470[/snapback]</div>

I am one of the "or higher" people, I use 91. its the highest here in Colorado. I always have and always will use a higher octane than recommended.

I think it has something to do with the fact that my first car was a 1971 Mercury Comet with a souped up 351W in it, that baby needed at least 100octane or it ran like crap.

besides isn't the higher octane fuels 'refined' more that way they can burn at a higher rating, what I am getting at is.....isn't it in a sense for 'pure' and free of extra crap.

 

That started with computer controlled fuel injection. The owners Manuel says 87 octane. The lower octane fuel actually burns faster and has more energy than higher-octane fuel at lower temps and pressures. The prius engine does not run at the same high compression and temps as a big v8 designed for extreme horsepower. The computer will adjust itself as best as possible to maximize performance but the engine is designed for lower octane. My guess is that you would not get the best mpg with high octane gas or at the least you would notice little or no difference so save the money.


Here is a link to a site for performance bikes but the info is still good. I am sure you can find more info with a simple web search but this was what I found with a quick search..
http://www.factorypro.com/tech_tuning_proc...e_vs_power.html

If you read to the bottom of the article you will see them talking about how to get 1 and 2 percent increases in power. That is because these guys are racing on closed circuit and that makes a difference when you are neck and neck with someone at the finish line but not for normal driving.

 

<div class='quotetop'>QUOTE(TomorrowMatters @ Mar 28 2007, 06:09 AM) [snapback]413479[/snapback]</div>

Sorry to tell you but higher octane gasoline is in no way more refined or more pure. It is just less prone to knocking due to a slightly different blend of distilled products.

There is one minor benefit to higher octane gasolines from top quality vendors (such as Chevron), the higher octane gasoline comes with a higher concentration of Techron - a cleaning agent that keeps carbon deposits in the intake and cylinders to a minimum. However, the extra amount is only relevant to dirty engines or to high compression / high performance engines.

In the case of the Prius, you are totally wasting your money on high octane gasoline (as well as energy resources - since it takes more energy to make higher octane gasoline). However, the car will benefit from a good quality gasoline and the detergent it contains (so spend your money there, rather than on the octane).

 

just use 87 from a top tier gas station and don't worry about it.

 

What if you live in CO and regular grade gas is 85 octane?

 

The Car Talk guys are always saying how buying higher-than-needed octane gas is a waste of money.

 

<div class='quotetop'>QUOTE(TomorrowMatters @ Mar 28 2007, 10:09 AM) [snapback]413479[/snapback]</div>

In Colorado, the altitude does make a difference.

But as for higher octane fuels being "better" than lower octane fuels...no. The cheap 93 octane gas bought from the no-name station is just as bad as the cheap 87 octane from the same station. Likewise, 87 octane Shell is just as good as 93 octane Shell.

It has nothing--NOTHING--to do with the octane rating. You see a bigger number and you think "bigger means better," but that's not so.