What is the Difference between Summer- and Winter-Blend Gasoline?

[Grumpy Bear]

1.7% energy content which translates to a like difference in mpg summer to winter. 

 

https://newsroom.aaa.com/2013/06/what-is-the-difference-between-summer-and-winter-blend-gasoline/

 

For mileage between 15 mpg and 30 mpg that's .255 to .510 mpg respectively. Not quite the hammer it's made out to be. Remember that gasoline is a Federally chemically defined substance for whom the EPA is the originator. If you wish to argue this take it up with them. As you will note in the link, if you read it all, it is their value that is so placed. 

Edited November 13, 2018 by Grumpy Bear

[Grumpy Bear]

In that AAA story is the statement that the refinery has to shutdown for the summer/winter-winter/summer RVP changes. An excuse for the cost of fuel. 

 

Lie. The change is done on the fly with minor changes to tray draw rates, a temp tweak here and there and Butane/Propane add percentage. I use to make this change twice a year. Takes less than a shift to do. Refinery operations cost in the thousands of dollars per hour. Maybe tens of thousands by now. No one is shutting one down for a minute when it takes a week to get it back on line and in spec from a cold boot. Specific units servicing 'reformulates' may be 'slumped' or process goals amended but shutting one of these bad boys down isn't in the cards. This isn't like, ops, burnt a batch of cookies. More like, 'crap the Hover dam broke'. 

 

You ought to see the knees and elbows scramble drills during a process upset to prevent this costly state of affairs. 

 

There is also a line on the 'annual' or 'bi-annual' shut downs for maintenance. Also not true. 'Turn arounds' are planned events done no more often that inspection and planning affirms. Like once ever 5 to 7 years. There is a ramp up in production to 'store' for the outage and heads roll if your one minute late on the start up target. There never short an ounce and plan to the gram. 

 

As an operator we didn't get paid for the few thousand hours we put in each year collecting samples and adjusting processes. We got paid for the 20 hours a year we acted like the Wizard of Oz during some crazy storm or equipment failures or fires...whatever it took to keep in not just running during the impossible but "IN SPEC" during the fight. 

 

Speculators push prices around....not operations. 

[CadillacLuke24]

Over the years I've grown very cynical of claims made similar to the effect of these. Thank you for the case in point, I will likely use it in future discussions. 

[Grumpy Bear]

16 hours ago, CadillacLuke24 said:

Over the years I've grown very cynical of claims made similar to the effect of these. Thank you for the case in point, I will likely use it in future discussions. 

Feel free to do so. 

[Grumpy Bear]

Today was unusual for January. 25 F and a dead calm wind. Just days ago it was in single digits and 40 mph winds. Give the chance I went for a two hour 100 mile jaunt down I-39 and back home. Some interesting observations. 

 

1.) I netted 30.6 mpg for the trip ONCE TO TEMPERATURE (reset after 25 miles). Just a bit more than 2% lower than my summer time numbers over the same route in like dead stick conditions after warm up. 

 

2.) Dialing up the GPH meter initial out of gear idle consumption was 1.20 GPH which pulled back to 0.80 GPH in the time it took to clear an exhaust temperature high enough to go closed loop and put the computer in control of timing and fuel mapping. 15 to 20 seconds. From here forward the idle out of gear fuel usage followed the viscosity profile of the motor oil reaching a usage of but .40 GPH out of gear at idle by 160 F EOT and never falling below that. In gear it climbed to .48 GPH. That is 20% more fuel at idle to turn the planetary over at a transmission fluid temperature of 118 F. 10% more than summer time at 95F.  

 

3.) My coast down distance from 45 mph to 30 mph in gear increases to over a city block longer at 25 F vs 95 F. The extra drag is two part. Cooler transmission fluid and....much cooler wheel bearing grease.

 

The lions share of winter fuel usage increase comes from viscous drag and NOT fuel composition.   

[cit1991]

Tires are made of viscous rubber too. As they roll, they flex, and as they flex, they turn work into heat.  All of which happens more at low temperatures when they're more viscous.