Fuel quality vs fuel economy (1 Viewer)

[Spike555]

Fuel threads come up often. I get my fuel at Costco 99.8% of the time because it is a Top Teir fuel and average’s $.30/gal less than anywhere else.
Some say that Costco dilutes their fuel with ethanol and that is why their fuel is lower in price.
So I decided to test this as best I could in a reasonable amount of time without going to far out of my way or wasting to much money.

So here are the stats on the truck.
2004 Land Cruiser
Michelin LTX A/T2’s at 50psi.
NGK Iridium’s with 40,000 miles on them.
K&N air filter.
Shell Rotella T6 5W-40 full synthetic heavy duty diesel oil, 8qts.
Castrol Syntec 75W-90 gear oil in the differentials and transfer case.
I always use premium.
Aircon is off.
I use my cruiser control everywhere. And I don’t drive like an @ss.

Sometimes my 20min commute takes 20min, other times it takes 60min.
I started with Costco because that is where I always get my gas.

 

[Spike555]

Next was Shell VPower.

 

[Spike555]

Then it was cheap grocery store brand fuel.

 

[Spike555]

Then it was back to Costco.

 

[Spike555]

My phone app did not put them in the order, bottom one is Costco the first time.
The next one up is Shell.
The top one is the grocery store brand.
Then the second from the top is Costco the second time around.

The only reason I can figure for the big difference in the first go around with Costco vs the rest is the switch from summer to winter blended fuel.

 

[Spike555]

And here are screen shots of Gasbuddy during the second go at Costco to show the price difference.

 

[Spike555]

So does fuel quality make a difference if fuel economy? Over the short term no. Over the long term possibly.
Top Teir fuels have more cleaners and detergents than cheap gasoline. So over the long haul I can see deposits reducing fuel economy.
Now I agree that the only way to do this and get better more accurate data is to do this test over more tanks of fuel and with the driver not knowing which fuel is in the fuel tank.

But here are the numbers. I entered everything except the price of the fuel, the app calculates that based on fuel bought and total cost.

I have no idea why the forum put the pictures in the wrong order in each post.

 

[CLEcruiser]

Too many numbers... But my 100 and my last 4runner got a full 1mpg less on the winter blend

 

[Couvi]

Very interesting. I have an 04 as well, stock except I went up a tire size. I average about 14, close to 15 with mixed city/highway (my commute is 40mi/day). I almost always get about 300 miles before the light comes on. I have a light foot, but do keep the ECT button on all the time. I also drive in 4 when in town most of the time. I use mid grade mostly, but do use regular as well. Thanks for posting.

 

[kelly saad]

This is cool, thanks for doing this. I personally only use high quality fuel, but it is interesting to see some testing done for different things.

 

[Dparo]

I will always opt for non-ethanol if I have the choice.

 

[planomateo]

I will always opt for non-ethanol if I have the choice.

Tough to do in Dallas / Fort Worth areas.

 

[KFunk740]

What I'd like to see is a comparison of different octanes, and analysis on whether premium increases fuel mileage enough to outweigh the added price.
(I mean, I really should do that myself, but I'm lazy and procrastinate)

 

[CLEcruiser]

It doesn't

 

[suprarx7nut]

What I'd like to see is a comparison of different octanes, and analysis on whether premium increases fuel mileage enough to outweigh the added price.
(I mean, I really should do that myself, but I'm lazy and procrastinate)

It doesn't

I tracked this over the course of ~2 years. One year with Regular and one with Premium. I did see a difference, but it's hard to catch. I haven't combed through the data formally yet, but as I recall the averages were about 1 MPG different and I suspect it will be statistically significant given how much data I gathered (every fill up for years).

The seasonal changes in gasoline blends seemed to make a larger difference than premium/regular, but unlike the fuel grade, you don't have much control over the blends available at a given time of year.

Spike, you should make a table or something. I'm sure you've got some interesting data there, but the current thread display makes it hard to make heads or tails out of it.

 

[Spike555]

I tracked this over the course of ~2 years. One year with Regular and one with Premium. I did see a difference, but it's hard to catch. I haven't combed through the data formally yet, but as I recall the averages were about 1 MPG different and I suspect it will be statistically significant given how much data I gathered (every fill up for years).

The seasonal changes in gasoline blends seemed to make a larger difference than premium/regular, but unlike the fuel grade, you don't have much control over the blends available at a given time of year.

Spike, you should make a table or something. I'm sure you've got some interesting data there, but the current thread display makes it hard to make heads or tails out of it.

I did the same test using regular vs premium as you, I only did it over the course of 11 tanks of fuel though. And like you I only saw 1mpg increase using premium vs regular.
Not enough to justify the price difference, but the owners manual does say “for increased performance premium fuel is highly recommended” and I can feel a difference in throttle response between 87 octane and 93 octane. And that extra “power” is nice when merging onto the expressway, passing on a two lane road or towing a trailer.
Obviously if you know you’re going to tow you can just put premium in and get the gains then and save the money for later.
But you cannot anticipate needing to pass someone.

Ethanol free is to expensive and the mpg increase it not worth the added $2/gal.

I used to keep track of my MPG religiously. For years. Then I stopped because I am happier not knowing. The trip computer is pretty accurate too. It was only off by tenth’s vs the app which is just fill in the blank.

@suprarx7nut if I knew how to do such a table I would. I posted the raw data because that’s all I know how to do.
If someone else can pull the data off of here and make a table go for it.

I realize my experiment is not perfect. But I think for general purposes it does the job.

 

[Spike555]

I will always opt for non-ethanol if I have the choice.

It costs to much here. Ethanol free is an average of $2/gal more than premium. I pay that for my small engines, but not anything for anything else.

 

[bpe3]

Gasoline is gasoline. It’s a commodity pure and simple. It’s highly likely that every single gas station in your neighborhood, or every your city/county/region gets its gas from the exact same distribution hub (AKA “The Rack”). The fuel comes to the rack via pipeline directly from a refinery hundreds of miles away. It sits in giant tanks waiting to get sold. At this point, it’s all generic gasoline, exactly the same. A tanker truck pulls up to the rack and loads up with 8-10k gallons of gasoline and ethanol. The actual amount of ethanol that is added is determined by state and federal regulations. Neither Costco nor your cheap indie station can adjust this mix to maximize their profit. At the same time, about 10-20 gallons of proprietary additives (Chevron Techron, Shell V-Power, ExxonMobil Synergy, etc.) are added to the mix. This is the only thing that makes fuel different from station to station. Gasoline is better with the right additives, but there is virtually no difference between the addives used by major gasoline retailers, including Costco.

Your MPG variance is being caused by something else.

 

[gatormark91]

Gasoline is gasoline. It’s a commodity pure and simple. It’s highly likely that every single gas station in your neighborhood, or every your city/county/region gets its gas from the exact same distribution hub (AKA “The Rack”). The fuel comes to the rack via pipeline directly from a refinery hundreds of miles away. It sits in giant tanks waiting to get sold. At this point, it’s all generic gasoline, exactly the same. A tanker truck pulls up to the rack and loads up with 8-10k gallons of gasoline and ethanol. The actual amount of ethanol that is added is determined by state and federal regulations. Neither Costco nor your cheap indie station can adjust this mix to maximize their profit. At the same time, about 10-20 gallons of proprietary additives (Chevron Techron, Shell V-Power, ExxonMobil Synergy, etc.) are added to the mix. This is the only thing that makes fuel different from station to station. Gasoline is better with the right additives, but there is virtually no difference between the addives used by major gasoline retailers, including Costco.

Your MPG variance is being caused by something else.

Additionally, if you put in Premium, and the ECU adjusts the timing curve a bit to take advantage of a little higher octane, there is absolutely zero way you could notice a few extra horsepower (and it's only a few, at best) in a 5500-6500 pound truck. Zero, nada, zilch. It's in your head.

 

[bpe3]

Additionally, if you put in Premium, and the ECU adjusts the timing curve a bit to take advantage of a little higher octane, there is absolutely zero way you could notice a few extra horsepower (and it's only a few, at best) in a 5500-6500 pound truck. Zero, nada, zilch. It's in your head.

Right and wrong. You won’t notice the difference between regular and premium fuel, but your vehicle absolutely will. Your mileage will be affected. Separate topic though. OP is talking about differences from station to station, not differences in fuel grade.