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Minimum Octane Levels
Recommended Octane Levels
KJ Engine (2.3L)
KJ Engine (2.3L)
KL Engine (2.5L)
KL Engine (2.5L)
Information on Octane and the K-Series V6
KJ: 91 (R+M)/2 minimum
KL: 87 (R+M)/2 minimum
Information on Use of Ethanol Blended (E-10) Fuels
Ethanol blended gasoline has downsides. It can reduce overall fuel economy by 5% or more. It is more susceptible to water phase separation. Many states in the US have laws that require service stations to specify on the pump that the fuel being dispensed is ethanol blended.
The use of E-10 has been made mandatory in the following US states:
Use of low ethanol content blended fuel is also mandated in Sweden, Paraguay, Thailand, Jamaica, India, Costa Rica, and Colombia.
Gasoline blended with oxygenates such as alcohol or ether compounds are generally referred to as oxygenated fuels. A common gasoline blend acceptable for use in the K series V6 is ethanol blended at no more than 10%. Gasoline containing 10% ethanol (ether alcohol) is typically marketed with the E-10 designation. Gasoline containing methanol and/or lead is not to be used.
Gasoline containing 85% ethanol, called E-85, is not to be used. Its lower carbon per volume content would require the fuel injectors to exceed maximum duty cycle under certain conditions. The ECU, unable to operate in closed loop fuel control mode, triggers MIL illumination with P0170/P0173 codes while long-term use can cause engine and/or catalyst damage. E-85 is only for use in "Flex-Fuel" type vehicles with engines designed to run on both gasoline and E-85. Flex-Fuel engines are equipped with larger fuel injectors and an ECU that detects which fuel is in use, controlling the fuel injectors accordingly.
The selection of octane ratings available at the pump can vary greatly from region to region. Generally, octane ratings are higher in Europe than they are in North America and most other parts of the world. This is especially true when comparing the lowest available octane level in each country. In many parts of Europe, 95 RON (90-91 AKI) is considered "regular unleaded," with 97/98 RON considered "premium unleaded."
In high altitude areas of the US such as the Rocky Mountain region, 85 AKI is considered "regular unleaded" while 91 AKI is considered "premium." This is because a naturally aspirated combustion engine draws in less air per cycle due to the reduced density of the atmosphere. This directly translates to reduced absolute compression in the cylinder, therefore deterring knock. A disadvantage to this strategy is that most forced induction vehicles are unable to produce full power, even when using "premium" 91 AKI fuel. In some east coast states in the US, up to 94 AKI is available. Often, filling stations near race tracks and drag strips will offer higher octane levels such as 100 AKI. Fueling stations in California and many other states offer 87, 89, and 91 AKI octane fuels, and at some stations, 100 AKI or higher octane sold as racing fuel.
In Germany, big suppliers like Shell or Aral offer 100 RON gasoline (Shell V-Power, Aral Ultimate) at almost every gas station.
In Australia, "regular" unleaded is 91 RON while "premium" unleaded is 95 RON. 98 RON fuel is also reasonably common.
In Malaysia, "regular" unleaded fuel is 95 RON while "premium" fuel is rated at 97 RON (Shell V-Power).
In the Netherlands, Shell V-Power is 97 RON (labeled as 95 due to the legalities of only using 95 or 98 labeling).
In Russia and CIS countries, 80 RON (76 MON) is the minimum available. The standard is 92 RON, but the most commonly used type is 95 RON.
In Italy, "regular" unleaded fuel is 95 RON (Verde) while "premium" fuel is rated at 98 RON (Super/Blu Super). Many Shell stations close to the cities also offer V-Power Gasoline rated at 100 RON.
In the United Kingdom, "regular" unleaded has an octane rating of 95 RON with 97 RON being widely available as "premium unleaded" (except in Ireland). Tesco and Shell both offer 99 RON fuel. BP is currently trialing the sale of "super-high octane" petrol called BP Ultimate Unleaded 102 with an octane rating of 102 RON. Although BP Ultimate Unleaded (with an octane rating of 97 RON) and BP Ultimate Diesel are both widely available throughout the UK, BP Ultimate Unleaded 102 is (as of October 2007) only available at 10 filling stations throughout the UK and is priced at roughly 2.5 times more than 97 RON fuel.
In other countries, "regular" unleaded gasoline is sometimes as low as 85 RON with 95 RON being more common and 98 RON considered "premium" when available.
Regional Variations in Octane Measurements and Values
This higher octane ratings seen in Europe are an artifact of a different underlying measuring procedure. In most countries (including all of Europe and Australia) the advertised octane shown on the pump is the RON value, but in the United States, Canada, and some other countries, the advertised octane is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 8 to 10 point difference noted above, this means that the rated "octane" in the United States will be about 4 to 5 points lower than the same fuel elsewhere.