[Giller]

From Government of Ontario Website:

"The Ministry of the Environment and Climate Change regulates the amount of ethanol found in gas sold in Ontario.
Gas companies, suppliers and sellers must include a minimum amount of ethanol in gasoline they distribute and/or sell.

By law, you must:
-maintain at least an annual average of 5% ethanol in the gas at all your facilities combined
-submit a compliance report to the government every year
-ensure that ethanol-blended fuel meets specific quality standards set out in regulations"
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I guess the key part of this is in the wording. Companies must put more ethanol in their lower brand and thereby can put less or none in their higher octane brands. As longs as they have 5% ethanol across the board - they just put 10% in the lower levels and that covers them.