When does the Winter Gas go away?
 

Has the Fuel blend in Colorado changed yet?
85 octane, always used
I've been getting better mileage lately. I've gone from an average of 16 to 17or 18 mpg which has worked out to = about an additional 50 miles per tank. In other words I was getting about 300 miles per tank and recently got 350 out of the last tank.
Here's the catch, I've been driving 80, in the mountains (Colorado) ,with the OD off !!(keep the Tranny happy) Up to this week, I've been driving really mellow, with subtle mpg improvement. But on the way home from this weekend's road trip I drove with minimal regard to fuel economy and got the best results yet. 85 octane, always used
This makes no sense. :dunno:
I did put in an Amsoil and cleaned the TB, that was a month and many tanks of gas ago.

Probably a combination of the lighter foot and warmer weather.I was wondering the same about gas formulations up here in Canada, as I've seen my best tank yet (300 miles).

when my mileage goes from 320 a tank to under 400 summer blend is back

I deliver fuel in Oregon, the valley area. We quit loading oxygenated fuel around march 18th If I remember. In oregon not every area gets oxy in the winter but some companys/stations use oxy all year long (arco comes to mind).

85?? ive never even seen that here. lowest we go is 87.

I think most gas stations around here have changed and 87 is the midgrade here.

I dont even think we get "winter gasoline" here. It's usually not extremely cold as you guys have to endure though here in SC.

i think april 1 is the change over, but i'm not sure. it usually says on the gas pump though. i think there's a sticker that says when they have the oxygenated gas.

your better milage in the mountains is a couple of factors:
1) summit county doesn't do oxygenated gas, so they have "summer" gas all year long
2) when you're at altitude you're brining in less air, so you're burning less fuel. for example: my subaru will top out aroun 28 mpg if i really take it easy on the highway. however, if i take it up over berthoud pass to winter park, i can easily get 32 on that trip, just because i'm spending a good chunk of time above 10,000 ft and the thin air means i can't burn as much gas
3) you said you got your bet milage coming home, if you were in the mountains, that's means coming home was mostly down hill.

"When does the Winter Gas go away?"
When you run out of Chili!

Sorry I could not resist.
Here in Ohio mileage and performance increase and pinging decreases when the winter fuel runs out. Usually around the end of April. It smells a little dofferent too.

Never here in DC/NoVA. We don't live in an EPA zone btu I think we still run winter blend gas all year long, easier for the distributors to deliver one gas to all the DC area.

thanks for responding. Let me clarify some details.
I bought the gas just outside of Alamosa (285&160) maybe it's still summer gas.
When driving at higher altitude, truck seems slower, so I have to drive it a little "harder" or higher RPM's to get desired performance. Wouldn't this offset any benefits of the thin air/less fuel burn?

I was driving 285, lots of up and down.

Thanks