Of the three types of gas avaliable in Alberta, 87, 89, 91, 87 is utterly rubbish for my 97 max. 89 and 91 are OK but 91 is a tad smoother during both cruising and idling. I'm about to engage a 2000 KM long trip and I would like to know whether 91 will provide better mileage on the highways comparing to 89.
Also, why is the 91 the highest available grade of gasoline here, and not the 94 in Alberta (or the entire Western Canada for that matter)? Thanks.
Depending on the vehicle there are insignificant or fairly major differences in gas mileage based on gas. I remember reading an article and somebody found that the saab they were testing with (supposed to have 91) got fully 7% worse gas mileage with 87.
If any car's manual recommends 91 then 91 is what that car's engine will run most efficiently on. This means more power and better mileage. Chances are that any mileage gained going from 89 to 91 will be more than offset by the increase in cost, but if you want to maximize distance on a tank of gas and your car asks for 91 91 is going to give it the best mileage.
In regards to why doesn't alberta offer 94 it doesn't really matter anyway because the majority of cars on the road ask for either 87,89, or 91. Going any higher on an engine that doesn't need it is simply wasting money. Afterall all octane does is retard combustion because it allows the gasoline to be compressed more tightly and if your car isn't making use of that higher octane anything above the capabilities of the car's compression is silly.
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What altitude are you at? Any engine needs fuel with octane rating
2-4 points LESS at altitudes above 3,000 feet so 93/94 octane is a pointless waste. Here in El Paso, at ~4,000 ft. altitude, no one sells fuel with octane higher than 91.BuddyWh
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