Octane difference?

Long story short, I have a 2018 CrewCab Limited, 4WD with 98K miles. I’ve run 87 octane forever. Today I was traveling cross country and the gas station I pulled in to only had 90 octane. After filling up I notice better response and was seemingly (according to the app) getting almost 2 miles per gallon more?! First, has anyone else noticed anything similar? Second, if I do put higher octane fuel in my truck, are there any negative ramifications? I’d be happy to pay a bit more for better performance if in fact, I’m not hurting my truck. Thanks in advance for the responses.

 

My 2 cents here: it isn't the octane it's the quality. Basically Exxon > Grocery store gas.

Unless you're supercharged...

 

Ive wondered about that... when I got the truck I went on a cross county drive, I put premium in it, and while at walmart I put in some 108 octane something or another. It felt quicker and i think i got a little better mpg.

 

Ah, the age old question about octane. Gasoline, no matter the grade/number, all have the same BTU. Meaning they all produce the same amount of power. Now Octane is the ability of the gas to withstand higher heat, which leads to dentition. Now in your case it could be a number of things. Engines over time build up carbon cause by shitty gas from no-name gas stations. Parts do wear out or lose their ability to function like brand new. Dirty sensors, spark plugs, O2 sensors, etc. Could you have gotten higher MPG with higher octane, possibly. But it was because something else is going on. The gas is just a band-aid. As for hurting your truck, well that's also debated. Higher octane gas needs more heat, spark and compression to get a full burn. If those things are not achieved then you are left with some raw gas after. This leads to clogged O2 sensors, which yours are out the door @98k, clogged catalytic converters among other things. I would hear people say, oh my old chevy with a gazillion miles runs better on 93 and doesn't ping/detonate any more. Well I can guarantee you it did do that when it was new on 87.

 

You're likely feeling the ECU adjusting ignition timing for the higher octane rating. These trucks don't have octane learning in the way that the 2020+ 4runner or 3GTacoma do for example, but they do have some octane learning capability to a limited extent like most vehicles, with the ability to adjust accordingly within a set range. Again, to a limited extent. It's not octane learning like what you're imagining when I say this.

You'd be surprised at how bad your KFB numbers can be on the stock tune with regular octane on just about any Toyota. Even if the ECU is pulling timing, it'll feel stronger when it's not pulling or adding, or even if it's just pulling one degree instead of 4 for example.

More power available can also translate to increased efficiency available, especially when shoving a brick down the highway.

Use the premium fuel, enjoy it!

There are some people who will die on their hill about premium serving zero benefit but that's simply not true, and there's actually quite a few Toyota vehicles with owners manuals noting what is already known: recommended best use with premium fuel for detonation reduction, thereby providing improved performance.

 

I am one of those that will die on the hill. My 2020 has had it all, 87,89,93 and non-ethanol 90, no difference except in my pocket. Octane does not produce power. Gas is gas. Only thing that matters is the gas station you get it from. Some have more cleaning agents than others and some don't have anything. His truck has 98K, its time for some maintenance. People want to drive vehicles to the ground and expect the same level of output, efficiency, comfort, etc as if it was brand new. It isn't going to happen. Quick true example in my area. 87/$3.42gal 93/$4.06gal. Driving 15k a year @ 15mpg with regular(87), cost $3420. Driving same miles but adding an extra 2mpg@17mpg would cost $3582. No benefit with 93. With those prices you would have to gain 3 additional MPG to be on top @$3383. 93 isn't going to gain you 3MPG better.

 

With tuning, it's certainly possible, but there are too many factors at play at any given time to say "it will net you an increase" with certainty.

Most people do understand this however.

That said, your example is dependent on cost. And that's fine. I respect that of course. Personally I don't care about the cost difference for premium and run it for the additional power and timing advance I have on my truck's tune, and I've observed an average fuel economy increase of 2-3 mpg when driving primarily highway speeds. City driving of course tanks it, as expected. I just like having the additional advance I can run on the premium fuel.

 

Usually when I drive cross country, I find Lower octane fuels, 86 and 85 (no higher), engine runs fine on those, probably due to the particular altitudes in the areas.

 

Yes, higher altitudes will have lower octane ratings available. Here in El Paso, we're at 4000ft and have 86. I've seen 85 in Denver and Colorado Springs, and in the Eastern Sierras.

 

85 octane is standard where I am, which it is sufficient for altitude. I ran it for several years except when towing heavier trailers in the summer. But I refuse to run it anymore. The vehicle idles smoother, comes off the line better, and putters around with a bit more pep without mashing on the gas when even just running 87. Where I notice the difference the most is at low RPM and cruising not the highway with a trailer. Sometimes I drive like an old man and keep it below 2k; sometimes I have somewhere to be but still keep it below 3k. And sometimes I just h'ain't care. When pulling a trailer, it will hold gear at lower RPM better. I'm not talking about MASSIVE differences - like dropping to 6th when it wants to be in 3rd gear, or feeling like the truck has an extra 80 HP - but enough that I notice a difference. Sure, gas is gas and it has the same amount of energy in it per gallon. But extracting that energy efficiently can be managed differently. I suspect that top end power isn't much affected by octane, but as others have mentioned, the engine pulls timing with lower octane fuels. Watching my gauges, I see the engine change the timing advance depending on octane.

 

@dirtydeeds

 

Does having an FFV engine have any effect on the above?
I ran mid grade until gas prices started getting ridiculous. Then I switched to bottom grade. Can't say I noticed a difference.
However I have a Toyota master mechanic in my family who says Tundras run better on mid grade.
By far most of my driving is high speed highway. If, long term, my Tundra will be better off with mid grade, I'll switch back to mid grade.

 

Our '14 4Runner seems to run smoother on 89 vs 87. The 4.0 isn't a speed demon to begin with, so I can't say it necessarily feels any stronger. Same with mpg, it may be better, but not by much.

I don't notice quite as big a difference in the Tundra, but it does feel a bit smoother on 89 as well. In both cases, the differences are felt more at idle/low rpm.

Also, neither one seems to gain anything more by using 90, 91, 93, 95 - unless those higher octanes are ethanol free, in which I have noticed a 2-3 mpg bump.

 

It's more about quality of fuel as others have stated, and it just so happens that the higher octane fuels in some cases are higher quality because they are marketed that way.

 

so im 61 and dont really understand all this ECU tuning stuff on the trucks. If you are currently running 87 octane and aren't having any detonation issues
wouldn't moving up in octane and paying the extra cost be useless and a waste of $$? Unless you have some super high performance mods like turbo or SC
like Sergei? (that guy with the 9/10sec tundra). Seems pointless.

 

go get some gas with no ethanol in it
https://www.pure-gas.org/
Got 28 MPG going across Nevada with it in my 2022 SR5

 

Usually modern PCM's have some kind of octane adjustment that will globally advance or retard timing vs the base tables based on its "detected" octane. It doesn't actually know you pumped in 87 or 91 or 93 octane but it can infer the fuels octane based on the knock sensors detection of knock. The engine will hunt for maximum timing and if it can run additional timing without knock then it will adjust to do that.

So yes, I would say that you can see an improvement running higher octanes, however, it will not be as dramatic as say running higher octane in the new 3.5L Twin turbo in the 3rd gen Tundra. Those run high compression(10.5 vs 10.2 for the 3UR) as well as boost because they are direct injected so, while they can run on 87, there is a tremendous amount of potential that can be unlocked at higher octanes. F150 Ecoboosts pick up almost 35 rwhp just from switching between 87 and 93 on the stock tune.

 

Without a 5.7 v8!

 

I'm pretty sure this is completely false. The energy density of gasoline does not change due to octane. Now there may be a better conversion from chemical to mechanical energy due to being able to run more advance, but the chemical energy available is the same regardless.

 

Before boost…..it made zero difference in my 2020

zero

I don’t think the timing changes unless you see continued knock. And then it’s only temporary

 

Yep. This is just one of many articles stating that:

https://www.edmunds.com/fuel-economy/to-save-money-on-gas-stop-buying-premium.html

 

This right here, lol. All grades of gas have the same BTU. And it not more octane=more heat potential, SMFH. And octane/grade has nothing to do with keeping your engine cleaner. My god, where do people come up with this crap. It almost 2023 and there is a wealth of information on the internet. It’s post like this that make other people believe this crap and waste money on nothing. This is is the funniest thing I have heard so far. Thanks for the laugh this morning.

 

And even today, manuf have made it possible to use 87 with boost. Stock OEM of course.

 

correct me if I'm wrong...Octane is merely resistance to detonation. nothing more.

spill a puddle of nitro methane....throw a match on it....it won't light.

 

In a nutshell, yes.

 

I almost always run 91 but that's mainly because I get gas from Costco and sams and to be honest it's usually still cheaper than running 87 at the regular gas stations.

 

87 Octane at a minimum and I'll pay extra for ethanol free. Most of what my truck gets is 91, but only because that's the most common ethanol free fuel that I come across. I'd be totally happy with 87 with no corn it in.

 

The biggest difference in 87 and 91/93 you'll notice is the truck won't pull timing to prevent knock so you'll have a bit more power under load. I can't remember exact numbers but it's a pretty significant change in timing advance.

I get 1-1.5 mpg better with 93 and 87 ethanol free. Both are anywhere from 60-80 cents per gallon more around home. Truck runs fine on 87 so that's what it gets 99% of the time.
Where I do spend the extra coin is towing my travel trailer. Mpg don't matter anymore with 7k behind the truck but it pulls a hell of alot better without trying to prevent knock all the time.

 

I have no experiance with Costco, but am pretty sure Sam's Club fuel in not "Top Tier" gasoline. For that reason I won't buy there.

I only use Top Tier 87 octane fuel. I do wish it was available with out the corn alcohol, but not the case.

 

I dont think it will improve MPG unless you are at higher loads. The engine shouldnt have much issue sitting at or near MBT at lower loads, it's only once the cylinders start filling with more air that the octane starts to become more important.

So I would guess this statement may not be true for daily driving but could be for towing where you are asking more from the engine.