I used 89 octane and my MPG has gone up 3 ticks already

[jpv74]

Just a quick hitter here folks. I understand the truck was designed to run on 87 but I have given her 89 octane twice and both times she definitely runs a little peppier and my MPG went up. Now in my area there is a substantial difference for 87 or 89 octane gas per tank so I have to decide if its worth it. My over all feel is that the truck will have less carbon build up and her internals will be cleaner on higher octane fuel. My truck is a 23 XL hybrid

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[Maverickman74]

Yeah ours gets at least 3 or 4 mpg better on 91. 10% cost increase for 12.5% mileage increase is good enough for me.

 

[jpv74]

She might get 91 for her birthday.....but for now she is livin large on 89

 

[surfstar]

Run five tanks, record your mpg, switch back, repeat. Try to keep driving style and temps similar. Repeat again and report back.
Never saw a diff for my vehicles, turbo, hybrid, NA. *shrug*

 

[EchoPear]

Jason from Engineering Explained has a really great video on fuel economy here:



Towards the end of the video, he illustrates why a small mpg improvement on an already high mpg car really has an almost negligible difference. Chances are, taking your 40ish mpgs to 43ish mpgs might be costing you more in higher octane gas than you are saving (in gallons saved, converted to gas prices)

What you can do to figure out if the higher octane is helping much, is top off completely, then travel exactly 100 miles and top off. Do the same route each with different octanes to see how many gallons per 100 miles you are using. You might be surprised that it’s a pretty small difference on the hybrid. The Ecoboost would probably benefit greater, as the base fuel economy is lower than the hybrid.

Just a thought

 

[Radman73]

My general theory is if you can afford it, put better gas in it. My wife's theory is exactly the opposite lol! So she drives her Acura on 87(and it is running fine) with occasional 91. Thankfully she doesn't argue 91 or higher on my Porsche. My Mav will run off of 89.

 

[Mike S]

What you see might not be a result of the octane difference, but rather how much Ethanol is in the different fuels you are using. Fuels containing Ethanol have less energy per gallon, so if your higher octane fuel has less ethanol, that might be why you are getting better mileage.

 

[Tim d]

Just a quick hitter here folks. I understand the truck was designed to run on 87 but I have given her 89 octane twice and both times she definitely runs a little peppier and my MPG went up. Now in my area there is a substantial difference for 87 or 89 octane gas per tank so I have to decide if its worth it. My over all feel is that the truck will have less carbon build up and her internals will be cleaner on higher octane fuel. My truck is a 23 XL hybrid

Curious if that 3 ticks offsets the increased cost per gallon?

 

[JanTheSexyVektan]

I thought you just weren't supposed to put higher octane fuel in than is specified. Is this some old myth?

 

[jpv74]

So just a quick reply to all of your replies....... I would agree that the uptick in mpg vs the cost of switching to 89 octane might be a wash or even a loss. That said my truck is no doubt running in a much better groove with 89 octane. As I mentioned before I think that running a higher octane may....just might....I have no idea.....but could......make the engine burn cleaner vs getting gummed up. There was some talk about PCV oil return not getting properly burned up or something.....which was over my head but as I recall the solution was to run the truck a little harder from time to time to help burn off the excess oil? Man that was a stretch for me to try to explain the PCV scenario but I ran with it. Long story short is that my truck will be running on alternating 87 and 89.

 

[Montana]

3 ticks.

I feel like this is a form of currency in a Rick & Morty version Earth variant somewhere in the multiverse.

 

[jpv74]

Ha! Actually it was 4 ticks! I went from avg of 44.3 to 44.7 in just a couple of days doing the same driving in the same heat. I strive for a 45 avg.......but have yet to accomplish that task as of yet. I just drive normal I dont try to stay in electric or anything like that.

 

[2xblueovalhybrid]

Octane is determined by two different measurements of how well a fuel resists premature combustion under pressure - the "research" octane number and the "motor" octane number. The "average" octane rating is what you see at the station (R+M/2).

When you pay for a higher octane you're paying for a fuel that is more resistant to combustion under pressure and is thus able to be compressed more in the cylinder. Higher combustion engines (like those with turbochargers) have higher compression ratios - higher compression ratio's require higher octane.

Putting low octane gasoline in a high compression engine will result in engine knock (i.e. your gasoline exploded before the cylinder fully compressed). Putting high octane gasoline into a regular compression engine won't really do all that much. Yes, maybe your engine computer will detect the difference and adjust accordingly but it won't make that much of a difference. So there is a LOT of downside risk, but little upside benefit for the cost.

In a quest for higher efficiency and power from smaller engines, more auto manufactures are making small turbocharged engines that they test and certify on mid-grade or premium for their EPA MPG tests etc. but also build them to run on regular. They're afraid of people's reaction to "Premium Required" when car shopping, so they instead label them as "Premium Recommended". So you can fill up with regular, and it will run fine, but you won't get the performance as advertised. ( I have a hybrid so I do not know what the Ecobost is rated for)

Also note - the octane rating of the gasoline has nothing to do with the "quality" of the fuel.

Gasoline is "fungible" and only varies on octane and it's destination market. That's to say the gasoline that comes out of Refinery Y and Refinery X destined for the same marked - are for all practical and reasonable purposes - chemically identical. They are comingled in petroleum product pipelines and then shipped across the country. There are some variances for emissions and pollution (like California has it's own gasoline formula). But for the most part it's all the same.

At the distribution terminals - or "rack" - proprietary detergents and chemicals are added to the gasoline just before it is loaded onto a tanker truck for deliver to a retail station. So in other words, your "Shell" gasoline only becomes a "Shell" gallon right before getting loaded onto the tanker truck.

At the rack is also where they add ethanol to most retail gasoline. Yes, most gasoline made at a refinery is sub-octane, and will only hit octane requirements with a splash of corn alcohol.

If you see a station with a tanker truck delivering gasoline, keep driving to another station. In the process of refilling, sediments that have fallen to the bottom of the underground tanks can be disturbed and make their way to the pumps.

Otherwise, regular, mid, or premium gasoline is of the exact same quality - with only one specific chemical specification differentiating them. If you worry about low-quality gasoline, buy a bottle of Seafoam and mix it in when you're filling up on occasion.

The "price premium" for premium is also increasing.

The U.S. Energy Information Administration collects and publishes weekly average retail gasoline prices - by region, grade, and formulation.

Since between 1995-2008, the difference in price for premium was about $0.20/gal. But since ~2009 that premium has only increased. On average across the U.S. for the week of August 14, 2023 - a gallon of premium was $0.83/gal more than a gallon of regular. It was as high as $0.94/gal as recently as October 2022.

So is that extra 2-3 mpg worth the nearly $1/gal extra?

 

[EchoPear]

Octane is determined by two different measurements of how well a fuel resists premature combustion under pressure - the "research" octane number and the "motor" octane number. The "average" octane rating is what you see at the station (R+M/2).

When you pay for a higher octane you're paying for a fuel that is more resistant to combustion under pressure and is thus able to be compressed more in the cylinder. Higher combustion engines (like those with turbochargers) have higher compression ratios - higher compression ratio's require higher octane.

Putting low octane gasoline in a high compression engine will result in engine knock (i.e. your gasoline exploded before the cylinder fully compressed). Putting high octane gasoline into a regular compression engine won't really do all that much. Yes, maybe your engine computer will detect the difference and adjust accordingly but it won't make that much of a difference. So there is a LOT of downside risk, but little upside benefit for the cost.

In a quest for higher efficiency and power from smaller engines, more auto manufactures are making small turbocharged engines that they test and certify on mid-grade or premium for their EPA MPG tests etc. but also build them to run on regular. They're afraid of people's reaction to "Premium Required" when car shopping, so they instead label them as "Premium Recommended". So you can fill up with regular, and it will run fine, but you won't get the performance as advertised. ( I have a hybrid so I do not know what the Ecobost is rated for)

Also note - the octane rating of the gasoline has nothing to do with the "quality" of the fuel.

Gasoline is "fungible" and only varies on octane and it's destination market. That's to say the gasoline that comes out of Refinery Y and Refinery X destined for the same marked - are for all practical and reasonable purposes - chemically identical. They are comingled in petroleum product pipelines and then shipped across the country. There are some variances for emissions and pollution (like California has it's own gasoline formula). But for the most part it's all the same.

At the distribution terminals - or "rack" - proprietary detergents and chemicals are added to the gasoline just before it is loaded onto a tanker truck for deliver to a retail station. So in other words, your "Shell" gasoline only becomes a "Shell" gallon right before getting loaded onto the tanker truck.

At the rack is also where they add ethanol to most retail gasoline. Yes, most gasoline made at a refinery is sub-octane, and will only hit octane requirements with a splash of corn alcohol.

If you see a station with a tanker truck delivering gasoline, keep driving to another station. In the process of refilling, sediments that have fallen to the bottom of the underground tanks can be disturbed and make their way to the pumps.

Otherwise, regular, mid, or premium gasoline is of the exact same quality - with only one specific chemical specification differentiating them. If you worry about low-quality gasoline, buy a bottle of Seafoam and mix it in when you're filling up on occasion.

The "price premium" for premium is also increasing.

The U.S. Energy Information Administration collects and publishes weekly average retail gasoline prices - by region, grade, and formulation.

Since between 1995-2008, the difference in price for premium was about $0.20/gal. But since ~2009 that premium has only increased. On average across the U.S. for the week of August 14, 2023 - a gallon of premium was $0.83/gal more than a gallon of regular. It was as high as $0.94/gal as recently as October 2022.

So is that extra 2-3 mpg worth the nearly $1/gal extra?

Good info I too was thinking higher octane resisted knock better, but couldn’t remember exactly why

This is how my mustang GT works, computer can detect octane levels and if it sees 91 or higher it adjusts something and I make like 10 more horses.

 

[LM42]

I thought you just weren't supposed to put higher octane fuel in than is specified. Is this some old myth?

Yes, it is a myth

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