2008 Prius fuel types

When it says premium it's refering to the quality of the gas NOT octane. It will run best on 87 octane (US). Actually putting a higher octane in it can cause problems, at the moment I cannot recall specifically what may happen. Bottom line is don't pay more for gas than you have to.

And congrats on your new purchase and welcome to Priuschat!

Any pictures to show us?

 

i had to use a high octane fuel in a generator once when there was no regular available and it caused all kinds of mishaps...get that stuff out asap

 

Regular gas works best, with the possible exception of high altitude driving.

Tom

 

Has anyone tried 89 octane to see if it offers any noticeable improvement over 87? My ICE-only vehicles always run better on 89, with improved MPG.

 

As stated above, Toyota participates in the advanced fuel formulation program, started by Shell. I personally think this program is all smoke and mirrors, because when fuel delivered to the stations has been tested by independent outfits, they found it to all be the same except for the additives put in when it was loaded in the tanker truck. The program calls their fuel "premium gasoline", not referring to the octane rating, but rather to the quality of the fuel.

I've used 89 octane rated fuel when regular 87 octane rated fuel was not available (they sold it at the same price as regular). I didn't notice any difference.

If you use 92 octane rated fuel it won't cause any problems. Usually there is some residual unburned fuel left after combustion, as it burns a little more slowly, though in an Atkinson cycle engine even that may have time to burn. If not the cat. converter will run a little hotter, burning up the residual. Your mileage may drop slightly, though I doubt you'd notice it.

Most modern cars will adapt to the fuel you put in after five or ten minutes of running. I'm not sure the Prius does, but I would be surprised if it didn't.

In conclusion, I think the only thing you'd notice is you spent a little more for fuel if you use premium 92 octane rated fuel.

 

In the U.S. and Canada, you would use 87 octane. The equivalent (research octane) in Europe and Australia would be 91. I was confused by that too when I read it. Here's an article that explains it.

 

If you're in the US you want the gas pump that says "87" on it in big letters. Ignore the fine print on the pump. Higher octane in a Prius is a waste of money.

If you notice pinging or knocking the car needs repair. Using higher octane for pinging only masks an underlying problem.

 

+1. 87 octane is just fine for the Prius.

 

Hi All,

The common octane improver these days is Ethanol. But octane improvers in general typically reduce the vapor pressure of the fuel. So it does not evaporate as quickly and create an explosive mixture before the spark lights it off.

How does this effect the Prius? It has a very quick starting method of operation. A fuel with a low vapor pressure may cause the starting to be not as perfect. And I think that would be an issue at cold temperature (below 10 F).

I though I read somewhere that the flex fuel vehicles have instructions not to use E85 at or below 0 F, as well. Besides the low vapor pressure, any disolved water in the Ethanol can crystalize out most likely, and cause fuel line freeze.

 

This is true. Here in the Central Valley in California, all the fuel is delivered from one central point. It is then that the different vendors add their additives to the gas making it "different". Thats why I laugh when people talk about how much better the "designer" stations gas is over say an Arco. Essentially, its the same thing.

 

Re: 2008 Prius fuel types (high altitude)

Two posters have suggested that operating at higher altitudes requires higher octane fuel. Actually, the reverse is true. In fact, in many locations at high altitudes, regular gas at most stations is 85 octane, not 87.

 

Re: 2008 Prius fuel types (high altitude)

This poster is correct. I had that backwards, which is what you get when you let a flatlander comment about high altitude (I do fly planes, but then they have mixture adjustments). The lower absolute pressure in the cylinders produces lower temperatures, so you can get away with lower octane gas. The other side of the condition is that your engine produces less power, so you have to give it more gas. If you have any sort of a knocking problem, it will be worsened by that.

Tom

 

FWIW, I did some steep mountain driving this weekend in eastern Arizona and western New Mexico. I had no problems with knocking at all, even accelerating uphill. The altitude varied from 1500 to 8200 ft.

 

If the additives are different then the gas is not "essentially the same" unless the additives themselves are "essentially" the same. Having said that, I buy gas at the most convenient station, without worrying about the brand.

I once went to a gas station where the hoses were reversed compared to what I was used to, zoned out, as I had something on my mind, and pumped several gallons of 92 octane gas before realizing my mistake. So I ended up with about half 92 and half 87. It didn't seem to hurt anything. But I sure would not do that on purpose. Higher-octane gas has less energy but costs more.

 

Re: 2008 Prius fuel types (high altitude)

No they don't, unless you're talking about toy planes. AVGAS, AVTUR, Jet A, A1, JP8, etc aren't allowed to be mixed with anything else when you fly real piston, turboprop, turboshaft, propfan or turbofans.

Another brilliant post from qbee42. Think before you type.

 

Re: 2008 Prius fuel types (high altitude)

Settle down, I believe Qbee42 was talking about the air/fuel ratio mixture.
I believe although I'm no expert, avation fuel has a RON of 100 where standard unleaded is 91RON and E10 94 - 95RON and premium is 98RON .

Lean mixture in piston aircraft can cause engine overheat and piston failure WHich has been blamed for several air crashes, while rich mixture uses more fuel and can foul plugs. The octane rating is fixed.

 

Interestingly, in the Australian market Prius user manual, it states on page 212 (discussing fuel requirements):

"Select Research Octane Number 91 or higher. For improved vehicle performance, the use of premium unleaded gasoline with a RON of 95 or higher is recommended."

So.... the there a benefit to using high octane gas >91 RON, at least in Australian Priuses? This user manual is for a 2007 model Prius.

I have read in these forums that Toyota doesn't recommend >91 RON petrol for the US Prius, but perhaps the Australian market Prius is tuned to take advantage of higher octane unleaded?

 

I suggest that you use regular 87 octane gasoline only, ideally from a Top Tier brand.
http://www.toptiergas.com/

See the following website that has various Toyota technical training documents available for download:
http://www.autoshop101.com/

Then open the Hybrid13 Fuel and EVAP System.pdf file. Page 3-4 of this file says: "For the Prius, use only UNLEADED gasoline with an Octane Rating of 87. Do not use premium gasoline. It may cause starting problems with the Prius. There is no gas mileage benefit when using premium gas!"

I am not aware that the Australian Prius gasoline engine is different than the US model. What are the hp and torque ratings in the published specs?

 

Yes, I'm aware of the technical documents posted by Toyota, but these may not be applicable to all market versions of the Prius.

According to Toyota Australia figures, the 1NZ-FXE engine on the Aussie Prius develops 57 kW @ 5000 rpm and 115 Nm @ 4000 rpm. The combined maximum hybrid power output (electric motor + petrol engine) is rated at 82 kW.

Perhaps the Aussie market Prius has different settings to take advantage of higher octane numbers, compared to other markets? After all, why would the owner's manual specifically state that a higher RON (95 or higher) would result in improved performance? Although, you could argue what is meant by "improved performance" (better power/torque? better fuel economy?)....

Just my educated guess