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Regular vs Premium/Ethanol vs Ethanol free

Here’s the question: Would long term use of premium gas cause any negitive effects such as mechanical issues with an otherwise sound motor requiring only 87 octane?

Here’s why I’m asking: I live in Wisconsin and regular gas uses a 10% ethanol blend, but premium doesn’t. I’ve found on a recent out of state trip that I got 7-8 mpg better on non-ethanol regular gas when available. Doing some quick math, all I’d need is a 2 mpg increase on ethanol free premium to break even on fuel costs. I understand that all things being equal, premium will not give any better fuel milage or performance on a car not requiring it. But that’s obviously not the case in my situation.

I can think of no negative effect for premium, so if the mpgs make it worthwhile, I’d use it.

Ethanol is know for lesser mileage. I dont believe premium will hurt anything. Why not just run non-ethanol 87 octane? did i miss something

“premium will not give any better fuel milage”

Higher octane doesn’t improve MPG, but no ethanol does improve MPG. The more ethanol in gasoline, the lower your MPGs will be.

OP gets a better value from running no ethanol. No ethanol gas isn’t available in 87 octane.

It’s not impossible, but it’s very hard to find non-ethanol 87 in Wisconsin, or anywhere else in corn farm country.

I may not have been clear enough. It’s near to, if not completely impossible to find 87 octane without ethanol in WI. At least I haven’t seen it where I live. There’s also a bill requiring it working through the state legislature I think. I knew ethanol lowered fuel milage, but I didn’t think it would be enough to be worth spending the extra for premium until my road trip.

“Higher octane doesn’t improve MPG”

Well, it depends. Often it doesn’t, but if the engine has a knock sensor and agressive engine timing maps the higher octane can give better mpgs by letting the engine run at more advanced timing. Just like the result from the old “time the motor by advancing the timing until it knocks under load, then back off a little” advice we used to follow.

That site might help you out, if you happen to live in one of the cities mentioned.

Besides if all the above is true if you are just breaking even, what’s the point?

I wasn’t just breaking even, I was saving several bucks a tank. To figure out if it’s worth it, the break even is 2mpg increase, so anything more would be pure savings.

That’s very surprising. In almost every city in Iowa, the ethanol-blended gas is 89 octane, and the 87 octane gas is non-ethanol.

The only adverse affect in running a higher octane fuel than recommended is carbon deposits on valves, so a fuel clean once in a while would be good.