Oregon-Washington: Winter gas ending, summer gas formula starting?
 

I've always wondered when "winter formula" gas season ends. It's never announced as far as I know, essentially a secret.

I saw this story about gas prices, but this quote caught my eye: "The region, she said, is also in the middle of annual refinery maintenance, slowing production before they switch to summer gasoline formulas. "The rest of the country doesn't move to the cleaner burning and more expensive summer fuels until late February or March," she said."

Source: https://blog.oregonlive.com/commuting...vers_face.html

Has anyone in Oregon and/or Washington recently noticed better MPG because "winter gas" is being phased out?

It is not a secret. The EPA regulates the formulations and has specific dates for specific parts of the country. I believe there are 3 formulations for us in the PNW, starting Jan 1, June 1, and Sept 15. I am not an expert but with a little googling there is a lot of information to be found. You may have to sift through some regulations but it should be all public domain.

Here's a map of dates I found for Kalifornia, for example.

https://energyalmanac.ca.gov/gasoline..._gasoline.html

Thanks for info! Obviously, I hadn't researched.

I would guess each formula change delivery to a gas station is blended into existing gas, so there is also a transition period until a gas station is completely pumping mostly one formula....

Yes, and stations don't get tanker deliveries every day, so there most certainly will be a phasing period.

I have been meaning to do research on this for a while now, but haven't found the time.

https://www.epa.gov/otaq/fuels/gasolinefuels/index.htm

https://www.epa.gov/otaq/fuels/boutiquefuels/index.htm

Here we go:

https://www.epa.gov/otaq/fuels/boutiq...utiquelist.htm

The EPA has national formulation restrictions from June 1 to Sept 15. State standards are referred to as "boutique" fuels and the last link appears to show them in detail. If this list is correct, it appears that OR and WA do not have their own regulations, and thus get only two blends per year.

I ran my scooter near out of fuel a few days back and as the station is 5 or 6 miles away I filled it with summer fuel I had in cans, it did not make any noticeable difference to the mpg, I have found though that there seems a point around 9 or 10c temp that mpg starts to go up or down.

blackfive, " I filled it with summer fuel I had in cans, it did not make any noticeable difference to the mpg" did you have stabil or some other fuel stability additive in the cans with your gas? For me the ethanol gas lasts about 2-3 months before I notice performance loss even in my garden equipment like my lawn mower, edger, and weed wacker that are hard to start with ethanol gas that is more than a season old if I don't add Stabil to it when I buy it. I used to buy gas 2 gallons at a time for my garden equipment and it would last me about a year, but now I buy it in 1 gallon increments and still have trouble when I get near the end of the can.