If you look closely at gas pumps across Massachusetts, you'll see a yellow sticker that says "10% ethanol". Regular gasoline in the state has been ten percent ethanol since about 2005.

What is ethanol and why is it in gasoline?

Ethanol is a kind of alcohol derived from corn, sugarcane or grain. It is added to gasoline to help reduce emissions. It does have a few downsides, however.

While ethanol in gas is safe for your everyday vehicle, it is not ideal for all gasoline powered engines.

What are ethanol's downsides?

Ethanol in gasoline decreases gas mileage.

One of the primary disadvantages of ethanol is that it is not as energy-dense as gasoline. This means that it has a lower energy content and is less efficient than gasoline. As a result, vehicles that use ethanol as a fuel source may not get as many miles per gallon as those that use gasoline.

Ethanol is corrosive to rubber hoses and some fuel systems. Gas with ethanol also has a shorter shelf life. Ethanol free gas is usually good for about six months whereas gasoline with ethanol will last three months. Ethanol also absorbs water.

One of the properties of ethanol is that, when left to sit for a period of time, it can absorb water from humidity or other sources. This is why boat owners prefer ethanol-free gasoline, and why it’s also preferred for engines such as lawnmowers.

These Mass. residents will pay $1 more for regular gas

Boaters!

I was talking to a guy who rents boats the other day and he was saying he pays nearly $5.00 for gas and I was confused.

Ethanol free gas (E-0) is about a dollar more per gallon. Sometimes less, sometimes more...

Ethanol free gas is not widely available at the pump, either. Here are some Massachusetts cities that offer ethanol free gas.

Arlington, Belchertown, Belmont, Bourne, Brookfield, Cataumet, Charlton, Cherry Valley, East Dennis, East Falmouth, Great Barrington, Hudson, Hyannis, Littleton, Lowell, North Falmouth, Pittsfield, Salem, Swansea, Wayland, Webster, Weymouth