Engine issue on takeoff.

All...check the EPA websites, they have literally volumes of data on auto fuels.  All auto fuels for the USA have a summer and winter blends.  Fuels with Ethanol are allowed a 1 point higher RVP (bad for us) for winter.  Most countries do not have summer and winter blends as the weather i far more stable in most countries.  The problems are that governments interference due to political pressures from big oil screw the consumer.  They give out exemptions to sell winter fuels in hot periods to sell off the fuel instorage.  I am aware of several fatal cases of aircraft in Texas a few years ago.  Unsuspecting flight schools stock up on cheap fuel (winter gas) to save money.  It gets hot and vapor lock happens.  Winter fuels are alway cheaper to make for the oil companies.  They have  a lot of Butane and that makes the engine start great  on a cold day.  The issue is it boils off at the first signs of spring.  

https://www.eia.gov/todayinenergy/detail.php?id=11031

This handy map shows what the change over date should be...however this at the refining level, it takes time to work into the retaill side downline to the pumps you get it from.  Adding to this issue is the exemptions that are written up. 

https://www.epa.gov/enforcement/fuel-waivers

Yes, it will make your head spin if you dive into it some more.   Kind of makes 100LL look good right?

Cheers

Hi RW,

"All auto fuels for the USA have a summer and winter blends."

Out of curiosity - why would the USA's southern states have winter blends?😈

In Arizona we don't have winter and summer. We have up to% all year. Plus I have two friends that test the alcohol amount on practically every fueling. It's always 6% - 7%. Only a few times at 8% and has never been 9%-10%. Ethanol here is added at the tank farm when a tanker is getting ready to make a delivery. When it comes directly into Tucson from the underground pipes it is ethanol free up to the tank farm. Arizona is one of the hottest places in the US, but dang few have vaporization issues. The summer month temps are usually 95F - 110F with the average every day temp at 100F.

Hi Roger,

Arizona has its own program they call CBG (cleaner burning gasoline). Parts of AZ do switch between Winter and Summer fuels, in particular Maricopa, Pinal, and Yavapai counties. They switch to summer fuel by May 1, and back to winter fuel in October, see link below. Also, careful not to conflate ethanol in fuel with the winter/summer program as they are two separate things. Winter and summer fuels differ in vapor pressure, not necessarily ethanol content. The primary difference is the quantity of butane (very light element of fuel) in the fuel formula. 

https://www.epa.gov/gasoline-standards/state-fuels

Sean Griffin wrote:

Hi RW,

"All auto fuels for the USA have a summer and winter blends."

Out of curiosity - why would the USA's southern states have winter blends?😈

Sean, the US has winter blend fuels as even in summer months as it gets cold at altitude.  For example when in New Mexico, a state just on the border of Mexico and the USA in the south west, the altitude is average elevation is roughly 5,700 feet above sea level.  They have mountains that are nearly 14,000 ft.  Naturally it gets cold enough to make fuels hard to start so they may need a winter fuel during parts of the year.  The same is true of many lower states in winter, cold temperatures lead to very difficult starting for engines. 

Cheers