Unleaded Fuel Octane Rating For XC60 T6

[Gravy]

G/day

Sales literature in Aus is providing mixed messages on whether this vehicle is compatable with standard unleaded petrol. A large price per liter compromise is required if the vehicle needs to be run on "premium unleaded".

Unleaded petrol in Aus has an octane rating of 91.

Premium unleaded octane rating varies between 95 and 98 pending on supplier.

Came across this comment on Aus "Fuel watch" site

NOTE: Higher octane fuels contain cleaning agents that are said to assist the removal of carbon deposits in a car’s engine and protect it against corrosion, allowing the engine to function better.

Further to the debate is the "ethanol blend controversy"

Appreciate some comment and feed back.


Gravy

[Jim314]

The owner's manuals on our Volvos state that US Regular Unleaded AKI 87 octane (RON 91-92) is the absolute minimum rated fuel, and the engines work optimally with AKI 91 octane (RON 95-96) or above. We use the recommended fuel. We drive conservatively and could probably get by with regular, but for the slight increase in total percentage cost of operation we use AKI 91 (RON 95-96). I don't want to worry that failure of a knock sensor could damage my engine. Neither of our cars is turbocharged. One is a 2004 V70 168 hp and the other is a 2007 XC90 3.2L (short inline six).

The fuel octane is more critical for a turbocharged petrol engine than a naturally aspirated one. If I had a turbocharged engine, I would definitely use the recommended fuel. The local Volvo sales people tell me they use US regular in their demos and personal Volvos. I think that they are worried that some buyers are put off by having to use premium gasoline. I trust the Volvo owner's manual over sales people.

In our locality the retail outlets only stock AKI 87, 89 and 93 (~equiv to RON 91, 93 and 97, respectively). My normal procedure is to mix approx equal volumes of 89 and 93. If I don't feel like messing with the pump twice, I just fill with AKI 93. On trips out west I sometimes could only get AKI 90 or 89 and I just used it, and didn't worry about it.

I habitually use Shell premium becasue of the claimed extra detergent in the "Top-tier" gasolines.

I don't worry about the presence of up to 10% ethanol in US gasoline. I accept the claim that the engines are designed to handle it. BTW ethanol is an octane booster as well as an "oxygenate" which reduces emissions. However, I don't think ethanol from fermentation of corn (maize) is really a "green" fuel because of all the soil erosion, fertilizer run-off, and extra energy in transporting fuel ethanol.

Research Octane Number (RON)
The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane.

Motor Octane Number (MON)
There is another type of octane rating, called Motor Octane Number (MON), or the aviation lean octane rating, which is a better measure[clarification needed][citation needed] of how the fuel behaves when under load. MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, a higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern gasoline will be about 8 to 10 points lower than the RON. Normally, fuel specifications require both a minimum RON and a minimum MON.[citation needed]


Anti-Knock Index (AKI)
In most countries, including all of those of Europe, and Australia, the "headline" octane rating shown on the pump is the RON - but in the United States, Canada, and some other countries,[which?] the headline number is the average of the RON and the MON, called the Anti-Knock Index (AKI). It may also sometimes be called the Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2.

Difference between RON and AKI
Because of the 8 to 10 point difference noted above, the octane rating shown in the United States is 4 to 5 points lower than the same fuel elsewhere. 87 AKI octane fuel, the "regular" gasoline in the US and Canada, is 91–92 RON in Europe. 93 AKI octane fuel, the "premium" gasoline, is 97-98 RON in Europe.

However most European pumps deliver 95 RON as "EuroSuper" or "EuroPremium" (equivalent to 90–91 AKI). In Germany, Great Britain and some other countries, 98 RON as "SuperPlus" (93-94 AKI) is available almost everywhere. Even 100 RON (95-96 AKI), is widely sold, and BP sell 102 RON, marketed as "BP Ultimate 102", at some very select few filling stations.
http://en.wikipedia.org/wiki/Octane_rating

[davew]

My T6 says minimum 95.

I think most people would agree through 98 is better.