Winter gas blend is back

[boldram]

Have not noticed in previous 2 years. This winter no matter what can not get above 16-17 mpg vs. 18-19. Same driving style, same route, same gas, same everything except for poorer mileage.
After reading AAA article i now know what caused this winter drop in mpg . Apparently winter blend gasoline is a culprit.
is it mandatory to sell winter blend in NJNYPA area during winter ? Can i find summer blend

 

[JF19Longhorn]

In South Jersey we've always had winter blend starting somewhere in Oct and not going away till Mar-Apr. Every year, never misses a beat.

 

[Jako]

Have not noticed in previous 2 years. This winter no matter what can not get above 16-17 mpg vs. 18-19. Same driving style, same route, same gas, same everything except for poorer mileage.
After reading AAA article i now know what caused this winter drop in mpg . Apparently winter blend gasoline is a culprit.
is it mandatory to sell winter blend in NJNYPA area during winter ? Can i find summer blend

Several factors involved.

The Difference Between Summer-Blend and Winter-Blend Gasoline

We’re talking about the cost differences between summer and winter gasoline along with how to save money on your fill-up.

www.gasbuddy.com

 

[RAM Patriot]

Winter-blend gas has a higher Reid Vapor Pressure (RVP) because the fuel must be able to evaporate at low temperatures for the engine to operate properly.

Summer-blend gas has a lower RVP to prevent excessive evaporation when outside temperatures rise."

What that means is that the refiners have to add butane to the winter gas so that it will ignite at lower temperatures making it more volatile in the winter.

This lowers the density of the BTU's meaning that summer blends have 1.7 percent more energy than winter blends.

 

[cerbo]

I think May 1st everyone has to be selling summer fuel. Summer fuel cost s more, below is a good read.

The Difference Between Summer-Blend and Winter-Blend Gasoline

We’re talking about the cost differences between summer and winter gasoline along with how to save money on your fill-up.

www.gasbuddy.com

 

[HSKR R/T]

I think May 1st everyone has to be selling summer fuel. Summer fuel cost s more, below is a good read.

The Difference Between Summer-Blend and Winter-Blend Gasoline

We’re talking about the cost differences between summer and winter gasoline along with how to save money on your fill-up.

www.gasbuddy.com

It's actually the opposite, winter blend costs more.

 

[cerbo]

It's actually the opposite, winter blend costs more.

you are correct, my bad.

WINTER GASOLINE​

In winter, gasoline blends have a higher Reid vapor pressure, meaning they evaporate more easily and allow gasoline to ignite more easily to start your car in cold temperatures. This blend is cheaper to produce, which results in lower gas prices at the pumps from late September through late April.

 

[BowDown]

I don't believe the winter blend myth for mpg loss. It seems to me that its DA or density altitude which corresponds to air temps. Colder air is denser which means there's more air in a given cubic foot. To maintain the correct fuel ratio in denser air, the PCM has to add more fuel, more fuel equals more fuel consumption.
For evidence of this I look at my own fuel mileage, a few weeks ago it when it was colder, 20-30°, I struggled to get 17 mpg in the city, it hovered around 16.8 mpg. The last couple weeks it's been 50-85° and I'm at 17.8-18.4 mpg making the very same trips in the same traffic using the same winter blend fuel.

I'm not disputing the differences between winter and summer fuel blends, just that it seems to me that air temp plays a larger role than the fuel blends

 

[Jmac509]

I don't believe the winter blend myth for mpg loss. It seems to me that its DA or density altitude which corresponds to air temps. Colder air is denser which means there's more air in a given cubic foot. To maintain the correct fuel ratio in denser air, the PCM has to add more fuel, more fuel equals more fuel consumption.
For evidence of this I look at my own fuel mileage, a few weeks ago it when it was colder, 20-30°, I struggled to get 17 mpg in the city, it hovered around 16.8 mpg. The last couple weeks it's been 50-85° and I'm at 17.8-18.4 mpg making the very same trips in the same traffic using the same winter blend fuel.

I'm not disputing the differences between winter and summer fuel blends, just that it seems to me that air temp plays a larger role than the fuel blends

Denser air and more fuel also means more power, so you would use a proportionally lower throttle input to maintain your speed. I believe everything would be equal.

I would be more inclined to believe the decrease of temperature increases rolling resistance of the drive train.

 

[RAM Patriot]

I don't believe the winter blend myth for mpg loss. It seems to me that its DA or density altitude which corresponds to air temps. Colder air is denser which means there's more air in a given cubic foot. To maintain the correct fuel ratio in denser air, the PCM has to add more fuel, more fuel equals more fuel consumption.
For evidence of this I look at my own fuel mileage, a few weeks ago it when it was colder, 20-30°, I struggled to get 17 mpg in the city, it hovered around 16.8 mpg. The last couple weeks it's been 50-85° and I'm at 17.8-18.4 mpg making the very same trips in the same traffic using the same winter blend fuel.

I'm not disputing the differences between winter and summer fuel blends, just that it seems to me that air temp plays a larger role than the fuel blends

The density of air depends on many factors and can vary in different places. It mainly changes with temperature, relative humidity, pressure and hence with altitude. The air pressure ( barometric pressure) can be related to the weight of the air over a given location.

Ambient temperature plays a crucial role in determining the performance of an engine. As the temperature increases, the air density decreases, resulting in a decrease in the mass of air entering the engine. This affects the combustion efficiency, intake air temperature, exhaust gas temperature, heat transfer, and ultimately the thermal efficiency of the engine.

 

[BowDown]

Denser air and more fuel also means more power, so you would use a proportionally lower throttle input to maintain your speed. I believe everything would be equal.

I would be more inclined to believe the decrease of temperature increases rolling resistance of the drive train.

Not necessarily, speed is a function of RPM. Power is how fast you can achieve that speed; that's evidenced by engine RPM regardless of temps.
You're turning the same RPM's at a given MPH; say 70 mph, in at 1600 regardless of ambient temperature.
In the summer, an engine would make less power than in winter based on air temps yet I consistently get better mileage in the summer and over the last week with the same fuel blend.

IDK about the drivetrain because once up to temp, it should be the same regardless of outside air. The same way your oil temp is the same in summer vs winter.

Regardless, I see a difference in mpg based on outside temps regardless of the fuel blend used.

 

[DEG]

I don't believe the winter blend myth for mpg loss. It seems to me that its DA or density altitude which corresponds to air temps. Colder air is denser which means there's more air in a given cubic foot. To maintain the correct fuel ratio in denser air, the PCM has to add more fuel, more fuel equals more fuel consumption.
For evidence of this I look at my own fuel mileage, a few weeks ago it when it was colder, 20-30°, I struggled to get 17 mpg in the city, it hovered around 16.8 mpg. The last couple weeks it's been 50-85° and I'm at 17.8-18.4 mpg making the very same trips in the same traffic using the same winter blend fuel.

I'm not disputing the differences between winter and summer fuel blends, just that it seems to me that air temp plays a larger role than the fuel blends

It's not a myth; it's a scientific fact that winter fuel is less efficient. It's just not the only contributor to lower winter fuel economy.

 

[BowDown]

It's not a myth; it's a scientific fact that winter fuel is less efficient. It's just not the only contributor to lower winter fuel economy.

Let me rephrase then, I don't believe its the largest contributor to the loss in fuel efficiency

 

[Jmac509]

The density of air depends on many factors and can vary in different places. It mainly changes with temperature, relative humidity, pressure and hence with altitude. The air pressure ( barometric pressure) can be related to the weight of the air over a given location.

Ambient temperature plays a crucial role in determining the performance of an engine. As the temperature increases, the air density decreases, resulting in a decrease in the mass of air entering the engine. This affects the combustion efficiency, intake air temperature, exhaust gas temperature, heat transfer, and ultimately the thermal efficiency of the engine.

I believe we are in agreement. I'm assuming you replied to add more detail to my previous comment.

 

[Jmac509]

Not necessarily, speed is a function of RPM. Power is how fast you can achieve that speed; that's evidenced by engine RPM regardless of temps.
You're turning the same RPM's at a given MPH; say 70 mph, in at 1600 regardless of ambient temperature.
In the summer, an engine would make less power than in winter based on air temps yet I consistently get better mileage in the summer and over the last week with the same fuel blend.

IDK about the drivetrain because once up to temp, it should be the same regardless of outside air. The same way your oil temp is the same in summer vs winter.

Regardless, I see a difference in mpg based on outside temps regardless of the fuel blend used.

I agree that the RPM is relative to the speed. The amount of fuel your burning to maintain that 1600 however is a variable.

Another theory could be the amount of time the vehicle spends warming up. I think the engine runs on the rich side at start up until it reaches operating temperature.

I don't disagree you see worse milage when it's colder. All I'm saying is I don't believe the engine burns more fuel because the intake air is colder.

By rolling resistance of the drive train, I'm not referring to engine oil temperature which I agree should be the same once warmed out upside regardless of ambient temperature. I'm talking about the differentials, wheel bearing assemblies, and rolling resistance of the tires. It's also possible the colder air being more dense could have slightly more aerodynamic drag.

 

[RamGuy32]

The density of air depends on many factors and can vary in different places. It mainly changes with temperature, relative humidity, pressure and hence with altitude. The air pressure ( barometric pressure) can be related to the weight of the air over a given location.

Ambient temperature plays a crucial role in determining the performance of an engine. As the temperature increases, the air density decreases, resulting in a decrease in the mass of air entering the engine. This affects the combustion efficiency, intake air temperature, exhaust gas temperature, heat transfer, and ultimately the thermal efficiency of the engine.

While the engine isn't as efficient, neither is the drag coefficient is higher resulting in more fuel being required to move the brick "aka RAM" through the air, in warmer times, the DC is less resulting in the vehicle moving through the air more efficiently. Helicopters have the same issue with colder and warmer climates and how it affects the lift of the rotor blades, and thus the carrying capacity of the helicopter. They prefer colder temperatures and the thicker air for the blade to bite against for maximum lift.

 

[RAM Patriot]

I believe we are in agreement. I'm assuming you replied to add more detail to my previous comment.

Correct, just wanted to highlight the fact that DA (Dense Altitude) had many more factors that just the temperature of the air; including, relative humidity and barometric pressure.

 

[RAM Patriot]

While the engine isn't as efficient, neither is the drag coefficient is higher resulting in more fuel being required to move the brick "aka RAM" through the air, in warmer times, the DC is less resulting in the vehicle moving through the air more efficiently. Helicopters have the same issue with colder and warmer climates and how it affects the lift of the rotor blades, and thus the carrying capacity of the helicopter. They prefer colder temperatures and the thicker air for the blade to bite against for maximum lift.

I agree with you about the truck has more drag moving through colder and more humid air, but that does not necessarily make the engine less efficient.

One of the effects of using NOS is to cool the air going into the combustion chamber. This is also the concept of a CAI (Cold Air Intake)


"Essentially, the basic reason to inject nitrous oxide is to increase the amount of oxygen in the combustion chamber, allowing for more fuel. When the liquid nitrous is released from the canister and expands into a gas, it cools and thus becomes denser, and once in the combustion chamber, the oxygen splits from the nitrogen allowing for more fuel and preventing premature detonation. More air = burning more fuel = more power. This is basic engine mechanics."

Nitrous Oxide: What Is It And How Does It Work?

Should you add NOS to your car, and is nitrous for cars safe?

carbuzz.com

 

[DEG]

The EPA Study below indicates winter fuel is 1.7% less efficient on average.

https://afdc.energy.gov/files/pdfs/2876.pdf

 

[BowDown]

The EPA Study below indicates winter fuel is 1.7% less efficient on average.

https://afdc.energy.gov/files/pdfs/2876.pdf

That's exactly my point, winter blend isn't that much of a factor in why the mpg efficiency drops in colder temps.
1.7% is decrease in fuel efficiency of .31 for someone averaging 18mpg or about a drop to 17.7 mpg.

As far as the engine working harder to push the truck through colder denser air, even with a tailwind I cant get my mileage up in cold temps so IDK about that

The Engine Has to Run Richer​

Gasoline has to vaporize in order to burn well in the engine, and gas doesn’t vaporize as easily in cold air as it does in warm air. When it’s cold out, the fuel mixture has to be “richer,” meaning there’s proportionally more gas injected into the engine than usual and, therefore, reduced fuel economy. This situation improves as the engine warms up, so it’s mostly an issue when the car is first started.

https://www.cars.com/articles/why-do-cars-get-worse-fuel-economy-in-cold-weather-475436/

How winter weather affects your fuel economy | Shell Australia

Here's how cold weather makes your car use more fuel – and what you can do to minimise the loss.

www.shell.com.au

A lot of the cold fluid claims really aren't an issue after 3-5 miles of driving yet my economy won't improve.