No... I use 91 pump octane (95 RON+MON/2=pump octane) which is ethanol-free. I do get better low end tractability, more usable torque and slightly better fuel efficiency. 93 would be overkill.

Ethanol-free gasoline is your priority... Are you in Quebec?

https://www.pure-gas.org/index.jsp?stateprov=QC

 

No. I am located at Northeast, USA, where our name brands like Shell, Exxon and BP only have 93 Octane, but no 91 Octane. So if I need premium, I will use 93. We don't have ethanol-free gas here,

 

All you will accomplish by using 93 Octane is taking more money out of your wallet. Chances are you will never notice the difference and if you do call it the ' Placibo ' effect.

 

You'll find that's almost a theological debate between believers and non believers. For heathen like me and most experts the fact is that higher octane has no more energy (it's actually the opposite), its purpose being to prevent knocking. Some engine configuration might need it in the first place as specified by manufacturer and some older worn or carbon deposit plagued may also benefit of it. Ethanol free, if available, is more the answer for an new engine engineered for 87.

 

You'll find that's almost a theological debate between believers and non believers. For heathen like me and most experts the fact is that higher octane has no more energy (it's actually the opposite), its purpose being to prevent knocking.

^^Truth.

I tune engines/ECU's as a side business. You only make power if the timing maps and fuel maps allow for it. Factory tunes do not as they are very conservative, to take into account the poorest possible quality fuel. Manufacturers always err on the side of caution.


OTOH, The Ford ECU's in high performance cars can listen for knock and ramp in timing (based off parameters in the tune) and take advantage of higher quality fuel. Usually only a few degrees of advance can be achieved this way and it is risky-not something OEM's typically do. This function is usually used inversely where a car is tuned for say 93, the knock sensors detect knock, and timing is pulled back until no knock is present in the case where lesser quality fuel is used. I don't believe Toyota ECU's do this but I'd be interested to hear someone's input "in the know" on Toyota ECU's.

 

I believe higher octane requires ECU flash for the updated fuel map for effectiveness, otherwise the octane increase doesn't do much other than it feels better.

 

If you want to try increasing octane to see if you can notice a difference in performance and/or MPG, I would also try a mid-grade (or custom mix your own at the pump). Even if higher octane did perform a little better, 93 may be overkill.

 

But theoretically a high compression ratio engine with 13 : 1 is better run with higher octane gas ?

 

That used to be – and still is in some cases – accurate as a general rule, but nowadays not all high compression ratio engines are equal in managing overheat in the cylinder chamber (the sole reason higher octane would be needed). Mazda and some Toyota’s hybrid versions even go to 14:1 on regular and Honda manage to do it with turbos.

The trick is in controlling temperature via admission/exhaust management. It’s done in a variety of ways, like using both direct and port injection in Toyota’s D-4S engine, according to demand. A bit simplistic, but let’s say it has its own ways of coping with higher heat in cylinder room rather than requiring a heat resistant (high octane) fuel.

Now if you were to regularly run your car for stretched periods of time on a race track, constantly on high load and rpm, DI part would be more solicited thus compromising heat management (and carbon deposit). Then, yes, higher octane would be preferable if knocking occur. But that’s not the most common situation…

One assuming his/her driving style is so “high performance oriented” could feel safer “investing” in higher octane as a “preventive way” (if that even exist) against knocking. Absolutely fine and certainly not harmful. The mistake would be to expect more performance from it.

The misconception roots in the long association between premium fuel and high compression performance cars (or ones announcing lower numbers for lower octane, as the ECU adapt). Therefore premium must be more performant? It’s rather the other way around: the car need premium because of the way it performs.

Unlike those, Corolla’s ECU sure adapts to knocking but won’t change its operation of the engine (“run better”) because of gas type. Having other ways than high octane to cope with heat, it runs perfectly fine on regular with the potential exception of some “extreme” uses, in which case premium would have to do with mitigation of consequences, not performance.

 

Because this is a high compression engine, I ran a test of my own.

Low vs High octane netted zero gains in mpg.

The funny thing is, in my last car (16 mx5 with 11:1 skyactive motor) premium actually gave me better gas mileage and perfomance. The one time I ran regular through it, it ran like dog crap, and barely pulled 20mpg in the city. But back to the Corolla- it doesn't matter.

Just save your money and throw in regular fuel. If you CAN find non-ethanol mixed fuel, run that. It's a world of difference. MPG is way better and the engines can produce the power a little smoother on it.

 

Running higher octane than an engine is designed for almost always is a waste of money. The only way higher octane can increase MPG or HP is if the regular gas makes your engine knock and it retards the ignition. I've run logs on cars during autocross and there were zero knocks recorded on regular gas. If your engine starts knocking when really hot outside and under heavy load, then maybe higher octane could help.



On ethanol (E10):
1) I hate the stuff for political reasons. That is for another discussion...

2) It will not damage your engine. It might have 2-3 decades ago, but times have changed.
3) Yes it can net you higher MPG, but most of the time the cost difference between E10 and Ethanol Free makes it more expensive on a $/mile calculation.

 

We have a few states that sell 85 octane. I think the statement in the manual about 87 or higher would mean you'd need to use mid grade 87 in those areas.

But I agree with the folks saying it's a waste of money. higher octane is not "better gas". It's a different chemical compound for a purpose. Like, oranges and grapefruits. One isn't better than the other. They're just differently constructed.
Having just said that, grapefruit sucks.

 

We have a few states that sell 85 octane. I think the statement in the manual about 87 or higher would mean you'd need to use mid grade 87 in those areas.

High altitude/mountain states like Utah, Wyoming, etc...
And it's fine in those areas.

 

My FRS has a 12.5 compression ratio and they recommend 93 ONLY, but can settle for 91 in places where 93 is not available. If you put anything lower than 91 the car will run horrible and possibly cause damage.


I just put 89 in my corolla hb.

 

I only use shell v power because it's ethanol free.

 

In your area maybe. In my area, definitely not. Pretty much every gas station has ethanol in their gas.

 

Just follow what the manual says for minimum octane. If the manual says 87 required. Then all you should put in is 87 as anything higher is just a waste. If the manual says 87 required and 91 recommended, then that means the engine management system can take advantage of higher octane fuels. But is still tuned to run on 87. You generally want to run as low an octane as possible before any knock occurs.

 

You meant that those Shell don't have ethanol free gas even now in summer.

 

All gas stations regardless of brand have Ethanol year round in their fuels in my area. We're in an area deemed to be a smog zone. As such the EPA requires under the Clean Air Act to have Ethanol/RFG fuels year round or the state loses Federal Highway funds.

There are some gas stations which do run ethanol free fuel. But I can count all of them on one hand.

 

recent 2020 LE corolla purchase Mid March and i do have to say that even though the car only requires 87 Octane, it drives like absolute hell (no matter which 87 brand of choice)
To me the pickup and knocking is so noticeable (especially if using COSTCO ...)

89 Octane runs just perfectly for me. Shell / Chevron seems to be just fine.
Arco & Costco for me is a BIG NO NO.

I do always give a fair test run of gas initially upon car purchase to see what works fairly and or plays nice.

 

What do you meant by pickup is noticeable ?

In my opinion, ethanol free gas in 87 should be better than 89 gas with 10% ethanol especially when the engine is under heavy load in manual transmission.

 

E10 year round here with summer and winter blends. only ethanol free is near marinas where old boats would basically be destroyed by the effects of the alcohol on their ancient fuel systems.

The new generations of technology allow for injectors to fire multiple times DURING THE COMBUSTION STROKE, which eliminates the benefits of higher octane because the multiple injections eliminate pre ignition and actually allow for combustion pressures to be controlled and eliminate most of the issues with high compression. Direct injection also allows for higher compression which means more power all the time. Understand that high compression is ONLY that high with no throttle restriction and some new systems with drive by wire even allow the throttle plate to be wide open with power output controlled by fuel delivery, egr amounts, as well as sequential injections during the dower stroke, which can only be produced by direct injection.

The goal is HCCI , homogenous, charge, compression ignition, which means significantly higher thermal efficiency overall and much better mileage. The higher compression is part of a comprehensive system, but the compression it allows is the "longer lever" which makes the charge expansion during combustion produce more power on less fuel. This goes far beyond the slower rate of burn with premium fuel, which produced power generations ago with high compression engines.

Run what you want of course, just understand that if there are no demonstrable results in performance or economy, then you are just spending money for no benefit. E0 may give you 6% better economy but for a price increase of many times 6% it's not worth it and power levels can be matched without it. Indy cars run on pure ethanol and they make ungodly power for their size. Alfa Romeo built an engine the year I was born that produced 400 horsepower out of 90 cubic inches AT 2 MILES PER GALLON. Now we can enjoy unreal power levels with complete driveability, reliability and very good economy, which in the future will increase another 25%, without any other aerodynamic or powertrain improvements.

You buy 5 gallons of gas for one gallon of work, 20% average THERMAL EFFICIENCY. Compare that to the 56% thermal efficiency of the supersize container ships, with 4000 ton engines running at 92 rpm consuming 285 TONS of fuel per day (3 foot bore 9 foot stroke). If they actually use the existing technology then they could get close to that thermal efficiency and even beyond. The giant diesels in those container ships run on bunker fuel, the nastiest diesel possible, barely, if even refined. In WW2 Japanese diesel subs pumped fuel into their tanks directly out of the ground, through a filter, unrefined.

The premium gas myth lives on, even my 98 year old father runs premium. I tell him it's a waste, he keeps buying it, so I don't expect to convince anyone here to not waste their money. Last trank in my 19 year old Echo was 50 mpg. I run the cheapest fuel I can buy and can measure no difference in performance or economy, but I can drive differently and choose different roads that are deserted and with no outside influences as far as traffic and no low load driving I can get a measured 120 mpg in my Echo by using pulse and glide techniques. I can demonstrate that to anyone who wants to call me a liar, just visit Williamsburg Va and contact me and we can ride in my car and I'll show you what I'm talking about and explain my patent, BUT I HAVE NO ENGINEERING DEGREE. IF THAT IS WHAT MAKES YOU THINK MY CLAIMS AREN'T ACCURATE THEN JUST IGNORE MY ADVICE. :grin:

 

A bit late to the party but whoa these engines have that high of a compression ratio? You'd think they'd be making more power, not that I'm complaining, I didn't buy my Corolla for the power; this thing is an absolute blast to whip around corners. Ethanol free gas is definitely the way to go, the Shell next to my job has a few 87 octane pumps without ethanol. I was forced to fill up with "up to 10% ethanol" gas today due to my dash saying "2 miles to empty". I'm not complaining, got my tank average up to 41mpg's!

 

oddly I always seem to have a feel upon the pedal when poor gas is placed in. Also sometimes feel a noticeable (and much louder RPM) struggle upon acceleration. It is hard to explain.

There is a great feature (shockingly) in the ENTUNE system that shows the gas mileage and estimates per trip, etc...
I have been taking note of this with all gas fill ups especially as I am still testing all different brands of gas for my Corolla.

I will upload some stats once i make the rounds of a few more brands.

Personally, I still seeing for me that 89 runs quite perfect.

ETHANOL gas have yet to see anywhere in town.

 

That’s why no Wawa gas for me. Only Shell for me.

 

I use only non-ethanol in my 2002 Echo Sedan, 295k miles. Better for the car than the ethanol blend. Mileage is better too. I use it not for the increase in the mpg or power, but for the longevity of my engine. The car was made to run on gas, so that's what I give it. The 60 cents above the regular no-lead price is worth it to me.

 

You have a choice of ethanol free and non ethanol gas in your area. Where are you?

 

I live in NC and most shell stations have an ethanol free pump, ive never bought any there so don't know what the octane is. Some if the Indy BP dealers also have an ethanol free 89 octane. I usually just run 93 octane just for the convience of not searching for ethanol free.

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Do you measure octane differently in the US?
In Australia we have 91, 95, 98, and E10. 95 and 98 are what we call premium.

 

So your 91, 95 and 98 is equivalent to our 87, 91 and 93.

 

Generally in the US octane is 87,89,93. Some locations, especially higher elevations have 85, and some have 91 as premium. Those are all e10. The only e15 I've seen is 88 octane. The only pure gas that ive used is BP which is 89 octane.

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Generally in the US octane is 87,89,93. Some locations, especially higher elevations have 85, and some have 91 as premium. Those are all e10. The only e15 I've seen is 88 octane. The only pure gas that ive used is BP which is 89 octane.

I did some research and found that the US uses a different system from most other countries, in Australia we use the RON rating. Everything here is pure petrol except for E10 which is RON91 with 10% ethanol ( about RON94) and E85 which is RON98 with 85% ethanol also known as flex fuel( about RON105). The fuel system in the US sounds like a complex guessing game.

 

In Ontario, only Shell 91 is pure gasoline (zero ethanol). All others use up to 10% ethanol. Source: https://www.shell.ca/en_ca/motorists/my-fuels/shell-v-power-nitro-plus-premium-gasoline.html

To the OP's first Q: has anyone actually tried running higher octane fuel for a longer time, so to achieve consistent long term fuel trim? What were the results? Better throttle response, mpg, better butt-dyno feel, etc.?

 

In Ontario, only Shell 91 is pure gasoline (zero ethanol). All others use up to 10% ethanol. Source: https://www.shell.ca/en_ca/motorists/my-fuels/shell-v-power-nitro-plus-premium-gasoline.html

To the OP's first Q: has anyone actually tried running higher octane fuel for a longer time, so to achieve consistent long term fuel trim? What were the results? Better throttle response, mpg, better butt-dyno feel, etc.?

I ran premium in my '16 Corolla for 2 months last "winter".
Zero difference.
I ran premium on a 3000 mile road trip a few weeks ago.
Zero difference.


The 4 cylinder Corolla, Camry, Tacoma, etc... do not alter timing to take advantage of higher octane fuel.
SOME Toyota V6 engines will.

 

I find that when it's warm to hot out, the higher octane normalizes power and response, similar to 87 in colder weather.



When the motor has to retard timing to prevent knock, the 87 will lose some power.