GAS-TECH. INFO FROM THE CANADIAN GEN. STANDARDS BOARD

VEHICLES AFFECTED: ALL WITH GASOLINE ENGINES -----------------

In Canada, at present, there are three types of gasoline available; Regular Leaded, Regular Unleaded and Super Unleaded. The gasolines also come in four volatility classes : A (summer), B (intermediate 1), C (intermediate 2), D (winter).

The general requirements for automotive gasolines are as follows:

Automotive gasolines are essentially composed of hydrocarbons but may contain additives that are designed to improve the characteristics of the gasoline. These additives include metal deactivators, oxidation inhibitors, icing inhibitors and detergents, as well as antiknock additives, for leaded gasoline.

The gasoline should be visually clear and free from undissolved water, sediment and suspended matter. Gasoline is also dyed so that different types can be visually distinguished from one another. Regular Leaded is dyed yellow or bronze, Super Unleaded is dyed green and Regular Unleaded is left undyed.

Where lead is added as an anti-knock compound to gasoline, it should not exceed 0.29 gPb/L.

The anti-knock index, which is determined through various tests, varies for different gasolines and for different Canadian regions. The anti-knock properties also vary by season. This ensures that all types of gasoline will meet the minimum requirements of an automobile, though some gasolines may vary in an attempt to make vehicles perform better.

How easily fuel vaporizes is also important. In cold weather vaporization should be easier than in hot weather. This is the reason for the four volatility classes of gasoline. At low volume gasoline stations, these volatility classes may not change as frequently as the cold turns to hot. It is possible that a winter class could still be pumped in the summer by these stations.

The following chart shows the different gasoline volatilities from month to month as they are available across Canada.

SEASONAL AND GEOGRAPHICAL SCHEDULE FOR VOLATILITY CLASSES ---------------------------------------------------------------------------- Geographic Area JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC

Coastal B.C. and D D D C B A A A B C D D Southern West

Northern West D D D D C/B B A B C D D D

Central D D D D C/B B/A A A/B B/C C/D D D

Southern D D D D/C B A A A B C D D

Newfoundland and D D D D D B B B C D D D Northern Quebec

Atlantic Coast D D D D C B A A B C D D

Northwest D D D D C B B B C D D D Territories and Northern Quebec

Artic Coastal D D D D D D C C D D D D

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Note: Where two volatility classes are indicated, the first class listed shall be supplied during the first fifteen days of the month and the second class during the remainder of the month.

There are many specifications for gasoline composition set out by the National Standards Board of Canada. These should help you further understand what goes into a grade of gasoline.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.