Fuel Requirement

I would hope this is not the case, as all the 'basic' gas in the midwest is also rated as '87 octane'. I would hate to have to spend more $$ for higher grade fuel.

As a side note, does anyone know if a Prius can use "E85" ethanol based fuel? If not, do we know why not?

 

Someone will have to doublecheck me, but I think I remember the manual saying ethanol was OK, but warning against using anything other than the standard 10% ethanol.

 

I use 87 in mine because that is all that is available. If 87 ruins the engine, then I'll ask Toyota and the Gas Companies to duke that one out. But frankly, I don't think 1 octane is going to make a difference unless you live in a high altitude, then you're fuel is likely 89 minimum anyway.

 

You might get a small amount of knock, but that should be picked up by the knock sensor and the car will retard the timing. Your fuel economy might be slightly worse, though, as igniting the fuel early reduces the amount of power and torque, so the engine has to rev harder (and consume more fuel) for the same output.

I don't know how Japan generally advertises fuel - is it by Research Octane Number (RON)? The number quoted by US gas stations is Anti-Knock Index or Road Octane Number, the average of Research Octane Number and Motor Octane Number (MON). MON is generally 8-10 points below RON, so AKI is 4-5 below RON. It could be that AKI 87 does actually meet the 82 RON requirement. It'll depend on the exact fuel.

Or put another way, this could be a bad translation to US customary units.

 

Looks like the new Prius needs plus type fuel over regular. This will add a buck or two every fill up. Good thing you get 50+ mpg. Did the gen 2 Prius manual ask for 88 octane as well ?

 

Based on what you posted Toyota DOES NOT recommend blended fuels... Most gasoline in the US is already blended with 10% ethanol, which is okay, but based on this I would NOT use E-85 fuel.

 

If memory serves me correctly, and I did just read the entire Gen II manual in late-March before getting my 2009, the manual says to ONLY use 87 rated fuel and NOT to use higher grade fuel. I'll have to doublecheck that in the manual but I remember reading it and making a mental note to myself.

 

As shown above, the manual suggests using gasoline with oxygenates. Ethanol-blended gasoline is acceptable, so long as the alcohol content does not exceed 10%. Most places that offer gasoline with ethanol are selling you E10.

To put it another way, E10 is fine, as it contains up to (or approximately) 10% ethanol. Another blend that has been proposed, and even offered in some places, is called E15. This contains 15% ethanol, and it is not OK to use, according to the manual. Because E85 contains 8.5 times more ethanol than E10, it most definitely is not part of the design for the Prius ICE, and it should not be used.

 

I'm certain you meant to write 92 RON, Mike.

I also think you are likely correct when saying that with the way the Road Octane Number is measured, use of 87 octane (AKI) is going to meet the Research Octane Number of 92.

 

This my first post. I have a '10 Prius on order. Might this URL resolve the octane issue?

pressroom.toyota.com/pr/tms/toyota/document/2010_Prius_Product_Info_FINAL.pdf

(this being my first post it will not let my post a hyperlink, but you can copy and paste)

87 Regular sounds good to me.

 

That is correct.

 

Well I am waiting anxiously to find out officially if we can use plain old 87 octane. We have no choice but to use E10 since all gas in this state is mandated to use 10% ethanol.

 

So when I need to bring my 2010 Prius in for service because either the engine died, or the catalytic converter got fouled up, or the heat recovery system doesn't work, and they run the codes to see I was using 87 octane instead of the specified 88 octane [and yes that data is recorded or dervied from other metrics], how do you think Toyota Service will respond when the manual explicitly states 88 - regardless of what the root cause of my service problem was?

I'm hoping that Toyota corporate will state that 87 is "approved" and that all of the Toyota service departments are in alignment - or the hardcopy owner's manual that comes with the car has the "87" figure.

 

The manual specifies high octane for my '07 GS 350 Lexus. However, from the very first tankfull I've been using 87 low octane without any apparent ill effects.

When a manufacturer certifies a car with EPA, whatever fuel octane used to obtain horsepower and milage must be recommended. A few years ago Car&Driver had a tv show. They tested low octane and high octane on a Porsche 911 Turbo. Their recommendations were to use low octane around town and save your dollars for high octane when you take your car to the track.

 

As others have chimed in, more than 10% ethanol blend is not recommended and could violate your new car warranty.

This comes from a new article in Business Week by the noted Car Guru Ed Wallace:

Last July was bad enough for motorists on a budget—gasoline prices had shot up to more than $4 a gallon. But for some the pain in the pocketbook was about to get worse. At City Garage in Euless, Tex., for example, the first of numerous future customers brought in an automobile whose fuel pump was shot. A quick diagnosis determined that that particular car had close to 18% ethanol in the fuel. For that unlucky owner, the repairs came to nearly $900. The ethanol fun was just beginning.
City Garage manager Eric Greathouse has found that adding ethanol to the nation's gasoline supply may be a foolish government mandate, but it has an upside he'd rather not deal with. It's supplying his shop with a slow but steady stream of customers whose plastic fuel intakes have been dissolved by the blending of ethanol into our gasoline, or their fuel pumps destroyed. The average cost of repairs is just shy of $1,000.
The Great Ethanol Scam in Businesweek.com

http://www.businessweek.com/lifesty..._autos+--+lifestyle+subindex+page_top+stories

 

That test is unreliable because it only will show short term effects of octane results. Lower octane will cause engine knock and can takes years to cause problems with engines. The Car & Driver guys cant afford a 911 turbo so of course they would do this test with a borrowed car. If they owned the 911 turbo then they would spend the extra 2-3 bucks per fill up. It's a $100,000 car why take a chance. The guys who write the manuals know what there doing and won't ask for something your car does not need.

 

You don't seriously believe that do you We all (at least many of us believe) that companies play a lot of games in order to get their spec's on EPA ratings as well as 0-60 times. They have to recommend what they test and certify with but I don't know of any modern computer controlled car that really had pinging problems dropping one grade of fuel. And if it doesn't ping it's not hurting it.

 

My last 3 cars had turbo engines and I noticed a difference every time in performance and fuel economy when using lower grade octane to save a few dollars at the pump. Maybe there is no difference with non turbo cars but saying if there is no ping the car is fine, is crazy. What about fuel pumps and injectors ?