Unexpected mileage gain using Exxon gas

[walterjay]

I have used Top Tier gas from time to time but usually not. The last four tankfuls I have given the car only Exxon 87. I had an unexpected gain of about 2 mpg using the gas. This came in spite of cooler weather where the mileage really drops especially when mixing in short trips.

So I am pleasantly surprised by the results. I have never noticed any increase with other top tier brands (usually Marathon).
For now I will continue using Exxon and see how it goes especially in the winter.

Has anyone else had a similar experience?

BTW the car is a 23 Tucson 2.5

 

[JavierH19]

Was it a full tank average driven in the same way?

 

[walterjay]

Was it a full tank average driven in the same way?

Yes

 

[MalibuRam65]

Must be the new Synergy ingredients they using now in there Gasoline ️

 

[Lubener]

You must have been traveling with the wind.

 

[shortyb]

Must be the new Synergy ingredients they using now in there Gasoline ️

Might not be far from true. Shell uses the nitrogen detergent in their Nitro+ premium to lesser degree in the lower octane products.

 

[Cujet]

I regularly get the best MPG with Shell 93

 

[walterjay]

I wish I had Shell available. Only one Exxon reasonably close. Everything else is WaWa and Royal Farms all over the place. Have a Sheetz coming soon.

 

[k1xv]

It might be differences in ethanol percentage.

 

[Escape08]

Maybe because of the cooler weather. People don't use car A/C this time of the year, an increase in gas mileage.

 

[spasm3]

You must have been traveling with the wind.

Traveling lol. In his private conveyance ?

 

[ATex7239]

Yes I’ve had this happen. Posted about it and people said it was all in my head. XOM has rewards point btw. You can get 3 cents back per gallon.

 

[IndyIan]

How not top tier was the previous gas station? I wonder if some end up with a lower octane than 87? And maybe the Exxon 87 was actually a bit higher than 87? A couple octane points can stop the engine from pulling timing or overfueling as much to stop ping. Also your driving habits can easily vary by 2 mpg.

 

[walterjay]

I have experimented with higher octane fuel only to see no change in mpg. My driving habits are consistent and do not vary. Same route, speed and behavior time and time again. And that is why I can point to the gasoline making a difference. It is the only real hard variable.

 

[Escape08]

I used to work in O&G industry here in Houston in the 1990s. The way it works, when a gas station order gasoline (assuming it's Exxon), they'll call the carrier. Then the carrier goes to the nearest terminal. Assuming the nearest gasoline terminal is operated by Shell, the carreir goes there to load fuel. The operator on the terminal will ask for loading cards from the carrier to verify what station it's going to. The terminal will give approval to the carrier to load fuel. Then he'll/she'll choose Exxon additives to be added with the fuel. The fuel is refined by Shell with Exxon additives on it to be delivered to the Exxon gas station.

 

[TheOilWizard]

Highly unlikely you gained 2 mpg solely by switching fuel brands. That whole correlation/causation thing.

 

[Cujet]

Highly unlikely you gained 2 mpg solely by switching fuel brands. That whole correlation/causation thing.

It is not only likely, it is common with some vehicles. Especially in some locations in NY where 93 is not 93 (due to mafia operations), and high compression engines then operate with reduced ignition timing.

Clearly here in South Florida, we have only 2 gasoline grades shipped here from LA ports. 87 and 93. We racers, engine tuners and nerdy types watch the data when different fuels are used. I can't tell you what Racetrak does to their gas, but it falls far short of Shell with regard to the 'number of timing pulls'. In layman's terms, Racetrak gas operates with less timing advance, and therefore lower MPG and less performance.

The same goes for local Costco gas. More timing pulls vs Shell. Lower MPG.


EDIT: It may be ethanol content as I don't test often, although my occasional casual graduated cylindrical flask tests show that 10% ethanol content is now the norm. I am not seeing E content lower than 9%.

 

[fantastic]

I get some of the best mileage in fall/spring type weather. It seems engines don't like too hot or cold.

 

[PF52]

Similarly, I filled up once years ago at a Marathon station in Chesterton Indiana and it felt like my car gained 50 HP. I never did figure out why.... Maybe I bought premium by mistake? Maybe the gas I bought had no ethanol? Maybe I always had the wind at my back for the entire tankful? Maybe someone slipped some happy beans into my coffee? I even sought out the nearest Marathon near my home hoping to duplicate the results, but no dice.

 

[shortyb]

EDIT: It may be ethanol content as I don't test often, although my occasional casual graduated cylindrical flask tests show that 10% ethanol content is now the norm. I am not seeing E content lower than 9%.

People think I'm weird when I show up with my ethanol tester . 3 stations within a quarter mile of each other have had zero ethanol in their 93 for the past few months. 2 of which I know are served by the same carrier. Best mileage and performance (seat of pants) is from the QT.