Volvo of Mississauga
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What fuel Should I use in my Volvo?


What type of fuel is best for your car? Its not a simple answer. Here is some information below to help maximize efficiency and longevity, and manage your pocket book!


Some Notes on Fuel grades for your car


A recent documentary on CBC’s Marketplace discussed the different fuel grades which are available in market today. There was significant suggestion that for average drivers that “premium” fuels provide little benefit to performance, emissions and engine cleanliness. Fuel quality and grades are very different discussions, and the documentary over-simplified the complicated science behind of fuel grades. It should be correctly noted however that average drivers in normally aspirated productions cars, should not expect to see huge gains by changing octane.


Octane grades are not a measure of quality or cleanliness. Octane grades measure a fuels resistance to combust based on compression and heat. In an internal combustion engine, ignition of the fuel must occur at a precise time, and it must occur when indicated by the engine management system based on a spark plug firing. Combustion must not occur due to compression. Modern engines have the capacity to adapt to different fuels, conditions and temperatures as needed.


Why does Octane make a difference?


Higher octane fuels are harder to burn, and they tend to burn more slowly. In a traditional engine, this translated to better fuel economy regardless of vehicle and engine type,  as all the fuel was more evenly burned. Few Hydrocarbons and unburned fuel therefore went out the tailpipe, and emissions were lower. The difference today is less drastic. Fuel metering and ignition system are extremely precise, and combustion in a engine is closely monitored by various sensors.


Some cars are naturally aspirated- they suck fuel and air into the engines without help. Some cars have forced induction- they have fuel and air actively pushed into the engines. Engines which feature the latter do so by employing either turbochargers OR superchargers. Forced induction raises the efficiency of the engine because it allows a smaller engine to produce greater power when demanded. There is however a cost. When driven hard, a forced induction engine creates more heat, and by their nature feature much higher combustion chamber pressures. It is these forced induction engines which require fuels that have a greater resistance to combustion due to compression.


The demands on a engine are variable. At low load times (ex. Easy driving and cool temperatures) almost all production cars will run happily on “regular” fuel. The difference becomes more apparent during times of high stress. High engine load, high temperatures, and high compression (in the case of a turbocharged car under hard acceleration) will all stress the fuel and cause some detonation. Detonation, more commonly known as “knock”, is a destructive force that will damage an engine very quickly because the fuel explodes before the spark plug ignites it. The knock sound you hear is the internal engine parts fighting each other because each cylinder is combusting fuel out of sync with the other cylinders. This causes engine parts work against each other and as they fight, the parts knock. Modern cars features a “knock” sensor which listens for a specific frequency sound and if detected, retards engine timing thus cutting power, and reducing the tendency to knock.


Anti-detonation sensors OR “knock” sensors only react once they hear detonation. This is done to preserve engine health. Knock sensor intervention will immediately scale back engine power. So in this case there is a performance difference.


Marketplace tested naturally aspirated cars on a dynamometer under very low load. The results they achieved were not surprising. In this case, Octane makes little difference as the fuel compressibility is not being challenged. Compare those results to a turbocharged car on a summer day, OR to a vehicle actively towing a trailer, a different result might have been achieved. It frankly, is an over simplification to say that the average driver does not require premium fuel. This really is a question of what type of performance and engine load will you be subjecting the vehicle to.


What fuel does My Volvo Need?


All Volvo’s currently in production will run on 87 AKI

Except: a) 2004 to 2007 ‘R’ series and b) cars with Polestar performance software


The Owner’s manual specifies this, however with some confusion.  In North America, 87 AKI is also known in ‘layman’s’ terms as “Regular”. The AKI or Anti-Knock Index is an average of the Research Octane Number (RON) and the Motor Octane Number. In North America, fuel is rated with a scale called the AKI or Anti Knock Index. That translates to:


87= “Regular”

89= “Midgrade”

91= “Premium”

94= “Performance” OR “Ultra”


In Europe, a different system of measurement is used called RON or Research Octane Number. The confusion comes because the numbers are very close to the AKI index. For example:


92 RON = 87 AKI

95 RON = 89 AKI

98 RON = 91 AKI


It is important that all vehicle owners consult the owner’s manual and follow the manufacturer’s recommended guidelines for Octane requirements.


Volvo’s owners books are European based, and as such often quote the “RON” number. People Read 92 RON and of course assume that that translates to “Premium” fuel at North American pumps. The reality is that they are two measurement systems that just happen to have numbers very close to each other.


Generally speaking, vehicle owners will get better mileage, performance and power with better fuel, but that has always depended on how you drive your vehicle. Light driving will yield little difference, hard driving with yield a much larger difference. Because higher octane fuels are harder to burn, cars not requiring them will be controlled by engine management software that must adapt to the slower burn time of high octane fuel. In this way, an average car being driven normally will not see significant fuel economy gains. Modern fuel injected cars, unlike their carbureted predecessors, can adapt and thus the economy gains can become negated.


Octane ratings are more important to cars with high compression, turbocharged engines. Hot temperatures, additional loads (such as AC, towing, hard driving etc.) all stress fuel and increase the potential for detonation. Premium fuel withstands more abuse of this nature. Owners will have to make the decision based on price and the kind of performance they are looking for from their cars.


From a cleanliness standpoint? Fuel producers tend to put more additives and detergents in premium fuel and for this reason, engines can be tuned to burn cleaner and leave fewer deposits behind that damage engine components, and contaminate oil. However, a car rated to run on 87 AKI will not see any appreciable differences in economy by adding octane to the fuel tank.


None of the above discussion negates the need for regular servicing, tune-ups and oil changes. These are critical parts of the economy and performance equation.





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