For most drivers, it's likely that the grade and price are the only bits of information on a gas pump that really matter.
But some outlets also proclaim that it's 'Winter Gas' you're pumping. Is that just more marketing hype... or is there really something to the claim?
In fact, there is. The chemical makeup of gasoline is even more complicated than how and why gas prices change. There are different fuels for different brands, different fuels for different areas of the country and different fuels for winter and summer.
It is not unusual to see big tankers from competing gasoline companies filling up at the same refinery. But that doesn't mean they're getting the same product. Just before that fuel is pumped into the truck for the trip to the gas station, a cocktail of additives unique to each brand is introduced.
Different climates and altitudes require different blending too. For example, higher altitudes can use lower octane fuel. And it is important to have the right fuel blend for the different seasons. Refineries have to adjust the fuel to cope with the colder winter conditions in different parts of the country.
The transition between summer and winter fuel begins in September to take into account the lag between refining, getting the fuel to distribution points and then to retail outlets. The switch back to summer fuel begins in April
What's the difference
So what is the difference between summer and winter fuel? Primarily it's volatility – the ease with which it vaporizes and can be ignited. Winter gasoline has a lower boiling or evaporative point, expressed as a measure called RVP (Reid Vapour Pressure).
The gasoline produced at a refinery is composed of a variety of chemicals or components. Each has a unique “distillation curve” or signature with the smaller or lighter molecules at one end and the heavier or more complex ones at the other.
The small ones have higher volatility and evaporate more easily – and at a lower temperature.
For summer fuel, when temperatures are high, too many light molecules or components would cause the fuel to evaporate more readily, causing the mixture to become rich and contributing to excessive evaporative emissions.
Conversely, those lighter components play a key role in winter where heavy molecules prevent the fuel from vaporizing readily with the associated problems of difficult starting and lean mixtures. For winter fuel, refiners increase the concentration of light-end components such as butane, propane, isobutene and other components with high oxygen and octane values.
In addition to juggling the mixture to emphasize heavier components in summer and lighter ones in winter, refineries blend different fuels to meet specifications required by federal regulations – and in some cases unique provincial, state or even municipal standards. Those regulations include things like minimum and maximum ethanol content.
In those respects most gasoline blends are relatively similar in terms of being 'Winter Gas'. But there may also be other differences between brands.
What else is different?
Once the basic fuel is refined to meet the applicable specifications and regulations it is pumped into tanks at a distribution centre. When a delivery tanker for a specific brand (e.g. - Shell, Esso, etc.) hooks up to a supply line, proprietary blends of stabilizers, detergents and friction modifiers, specific to that brand are also added.
The stabilizers keep the various components within the fuel from reacting with each other and forming deposits or gums that can stick to valves or combustion chambers.
The detergents are designed to help clean the combustion chamber and valves, removing any “gunk” that may have been created. The friction modifiers are meant to coat cylinder walls and help the pistons and other moving parts slide more easily.
Some cut-rate outlets may keep their prices down by skimping on such additives.
Some brands may vary their additive packages to optimize performance in winter months. They may also add what's commonly called "gas-line antifreeze" to help prevent icing. It's those additions that may differentiate one brand from another and prompt them to label their product as 'Winter Gas'.
So the next time you stop for a fill-up give that fuel some respect!
SOURCE: AUTOFILE.CA | RICHARD RUSSEL
But some outlets also proclaim that it's 'Winter Gas' you're pumping. Is that just more marketing hype... or is there really something to the claim?
In fact, there is. The chemical makeup of gasoline is even more complicated than how and why gas prices change. There are different fuels for different brands, different fuels for different areas of the country and different fuels for winter and summer.
It is not unusual to see big tankers from competing gasoline companies filling up at the same refinery. But that doesn't mean they're getting the same product. Just before that fuel is pumped into the truck for the trip to the gas station, a cocktail of additives unique to each brand is introduced.
Different climates and altitudes require different blending too. For example, higher altitudes can use lower octane fuel. And it is important to have the right fuel blend for the different seasons. Refineries have to adjust the fuel to cope with the colder winter conditions in different parts of the country.
The transition between summer and winter fuel begins in September to take into account the lag between refining, getting the fuel to distribution points and then to retail outlets. The switch back to summer fuel begins in April
What's the difference
So what is the difference between summer and winter fuel? Primarily it's volatility – the ease with which it vaporizes and can be ignited. Winter gasoline has a lower boiling or evaporative point, expressed as a measure called RVP (Reid Vapour Pressure).
The gasoline produced at a refinery is composed of a variety of chemicals or components. Each has a unique “distillation curve” or signature with the smaller or lighter molecules at one end and the heavier or more complex ones at the other.
The small ones have higher volatility and evaporate more easily – and at a lower temperature.
For summer fuel, when temperatures are high, too many light molecules or components would cause the fuel to evaporate more readily, causing the mixture to become rich and contributing to excessive evaporative emissions.
Conversely, those lighter components play a key role in winter where heavy molecules prevent the fuel from vaporizing readily with the associated problems of difficult starting and lean mixtures. For winter fuel, refiners increase the concentration of light-end components such as butane, propane, isobutene and other components with high oxygen and octane values.
In addition to juggling the mixture to emphasize heavier components in summer and lighter ones in winter, refineries blend different fuels to meet specifications required by federal regulations – and in some cases unique provincial, state or even municipal standards. Those regulations include things like minimum and maximum ethanol content.
In those respects most gasoline blends are relatively similar in terms of being 'Winter Gas'. But there may also be other differences between brands.
What else is different?
Once the basic fuel is refined to meet the applicable specifications and regulations it is pumped into tanks at a distribution centre. When a delivery tanker for a specific brand (e.g. - Shell, Esso, etc.) hooks up to a supply line, proprietary blends of stabilizers, detergents and friction modifiers, specific to that brand are also added.
The stabilizers keep the various components within the fuel from reacting with each other and forming deposits or gums that can stick to valves or combustion chambers.
The detergents are designed to help clean the combustion chamber and valves, removing any “gunk” that may have been created. The friction modifiers are meant to coat cylinder walls and help the pistons and other moving parts slide more easily.
Some cut-rate outlets may keep their prices down by skimping on such additives.
Some brands may vary their additive packages to optimize performance in winter months. They may also add what's commonly called "gas-line antifreeze" to help prevent icing. It's those additions that may differentiate one brand from another and prompt them to label their product as 'Winter Gas'.
So the next time you stop for a fill-up give that fuel some respect!
SOURCE: AUTOFILE.CA | RICHARD RUSSEL
