Sunoco Octane 94
 

I fill up at Sunoco with Octane 94 in all my cars and bike. But I realized that the milage is at least 10%-15% less than 91 Octane (Shell/Esso).

My question is, shouldn't Octane 94 have better milage compared to 91 Octane? Or Octane 94 just makes the engine burn more fuel to get more power?

Which Octane would you use?

Octane and economy are not exactly related, but could be. Heat value of the fuel will give you the economy, and the higher octane will give your engine the ability to make more power (more spark advance). In general, higher octane fuel also has more heat value, so should give you more economy. If you don't find the 94 octane is giving you any more power or economy, you are paying extra for nothing. People often confuse octane and power as being synonymous but may not depending on the engine. Octane rating is the ability of the fuel to resist pre-ignition, nothing more. Diesel, as an example, is a high octane fuel but obviously not proper for a "gasoline" engine due to many other properties. If your engine does not require high octane (higher compression), then don't waste your money. I've been using Shell 91, and all is working fine.

Does Octane 94 burn cleaner than Octane 91? Will Octane 94 be better for the engine or makes no different?

Octane and "cleaner" are not really related. Detergent additives and making proper spec. gas determine how clean it burns. 94 octane will only be better for the engine if it requires higher octane due to pre-ignition problems. i.e. higher compression. If your engine does not have to auto-retard the timing due to engine pre-ignition (knock) with 91 octane, then there is no advantage to the 94 octane gas. If, however, your motor is knocking on 91 octane gas, and does not on 94, then the 94 octane gas is better. Generally, the major fuel makers will have the better detergent additives, so stick with the majors. The discount fuel sellers (grocery stores) will not be getting the upper end additive packages but all fuels in Canada have to meet the CGSB minimum spec. Hope that helps.

Great Help! Thanks for the info.

You folks in eastern Canada should consider yourselves lucky. Here, where we grow the damm stuff in the ground, there is a shortage. I was on my way back from the Rocky Mountains this afternoon and I decided to get some gas. I stopped in Hinton.... no premium in town (9 stations). Then I stopped in Edson.... it took 12 stations before I found some premium.

Absolutely ridiculous! There was some storm damage at the Petro-Canada refinery in Edmonton about two weeks ago. Now, there are some stations that have no gas at all. Because the 370 takes only premium fuel, I was getting kind of worried after 21 stops to find the right kind of fuel.

It's the 1970's here in Alberta again.

You can limp around without Premium if you need to get home....