You shouldn't use 86 or 85 grade gas, right?

No doubt performance could be a little better the higher octane however from a safety of the engine standpoint there is zero data that I have seen. When I was young, dumb and poor I had a turbo engine car that they said needed 92 octane (actually 93) but in Commiefornia even back then prices were high. I used 85 all day every day, drive like an idiot and absolutely nothing ever happened to that engine.

People running higher octane because they think there engine will blow is an indicator that the industry has done a great job fearing you into spending more for higher octane.

Give me day and prove me wrong. Not some anecdote etc etc. Real data comparing one engine running on lower octane and one on higher and show me pictures of the inside. While the internet is vast I am never seen any data.

Again not talking about performance etc. Just the health of the engine after tens of thousands of miles.

My point is if you want to use 85 in a turbo engine there is nothing you are going to do in what type of daily driving you do to make any difference in the health of your engine. That’s my opinion.

 

Show me your evidence first.

Folks, just run what the manufacturer says you should if you have an EFI or DI engine. Here's an SAE study saying just that.

And here's a quote from the US Department of Energy - "The sale of 85 octane fuel was originally allowed in high-elevation regions—where the barometric pressure is lower—because it was cheaper and because most carbureted engines tolerated it fairly well. This is not true for modern gasoline engines. So, unless you have an older vehicle with a carbureted engine, you should use the manufacturer-recommended fuel for your vehicle, even where 85 octane fuel is available."

Give me day and prove me wrong. Not some anecdote like in the quoted post etc etc. Real data comparing one engine running on lower octane and one on higher and show me pictures of the inside. While the internet is vast I am never seen any data.

 

Call me irrational, but the wide variance of opinion found in threads like this, oil change intervals, and cool down as they pertain specifically to turbocharged powertrains, only serves to reinforce my long-held bias to never, ever buy someone else’s turbo, second hand. And I’ve owned a lot of turbos.

Certainly wouldn’t recommend being first in line to take out a used car loan out on TFL’s Tacoma….

 

Amen to that.

Threads like this are why I don't buy used cars period. I'd rather buy new and keep it for 15 years.

 

Sorry, this is a blend of anecdote and data. I know for a fact at least in 2004 manufacturers were capable of estimating "high"/"low" octane with their ECUs. The ECUs had different timing and fuel maps dependent on that measurement (as you would guess). As an engineer, I don't think you would take the risk that somebody wouldn't put the shittiest grade gas in their tank they could muster, even if you made them get a tattoo of "91" on their hand. It's now 20 years later... I would hope Toyota divisions talk to each other.

 

Unless someone goes through the trouble and great expense of setting up a controlled experiment that replicates somewhat average real-world conditions, including varying loads, temps, humidity, cycles, etc., and keeping all variables the same (fuel additives, motor oils, etc.), we are never going to know what the inside of an engine looks like when using the different octanes. And this would take years to execute.

Some places up in the mountains still sell 85 or 86, and sometimes it is the only octane available. It works in a pinch, and if you fill up with higher octane when you can it will likely not cause any harm at all.

Carbureted engines needed either lower octane or an adjustment to lean the mixture out at high altitudes. I was accelerating out of the gift shop parking lot at the top of Monarch Pass in a '65 Mustang and learned first-hand what can happen -- the engine flooded and cut out right as I pulled out into traffic. It was a pucker moment for sure, but luckily it kicked back in and I went lighter on the throttle.

Modern fuel-injection manages this automatically now, and it can also compensate some for the lower octane in most cases.

The performance numbers posted above show that there is a difference, so those that say "you are just throwing your money away" should take note. But again, we'll never know the truth about engine longevity without a valid experiment. My guess would be that the engine running the higher octane would last ~5%-10% longer. That's my opinion, anyway.

Same. I only buy new. I have trust issues. Well, I did buy a used Corolla for my daughter, but it's her first car and first cars have a tendency to meet an early end. Trust issues at work yet again.

 

Most engines do not have any way to directly measure the octane rating of the fuel they consume. Instead they rely on a reactionary process to engine knock. The motor needs to knock before knock sensors kick in and tell the ECU to pull timing, so there's time for damage to happen before a motor can react to the wrong gas being put in it.

That's if it can react enough or quickly enough to mitigate the damage you do. On the previous page of this thread, there's a post sharing a link to a story about a Cadillac blowing up on a press drive because the journalist put regular in it.

She takes premium dude. PRRRRREEEEEMIIIIIIIIIUUUUUUMMMMMMMmmmmmmmm

A few posts up from this one, I shared an SAE study that worked with a research engine. They compared the octane needs of both carbureted and EFI engines at various elevations and came to the conclusion that EFI motor mitigates the affect of altitude on octane requirements. In other words, always run at least the manufacturer's recommended octane in any EFI or DI car.

 

You're correct. The "adaptation" is the difference, verses say my 1999 Taco, where it has no concept of octane or multiple maps, it just brute forces ignition advance over time until it knocks and backs off. The last thing you'd want to do is give the (any) ECU no time to determine your change, like switching from 93 to 85 and flooring it repeatedly.

 

This vehicle and all older Toyotas back to ~2000 use reactive means with both short-term and long-term adaptive capabilities to combat knock related to fuel quality (octane). Through custom programming (tuning), you can 'default' the system to skew the default calibration to values appropriate for use with premium fuel or you can skew that setting to default values appropriate for lower-octane regular fuel.

 

Yes that's true, but it's out of scope for a discussion about stock motors on factory programming. Custom tunes are a whole different can of worms.

I just say why run an out of spec fuel at all when the manufacturer, SAE, and fed all say it's a bad plan. All of the data in actual studies say to not do it in EFI and DI motors. So what's the point in taking the risk? Motors are expensive, the cost increase between 85 and 87 in the mountains isn't.

 

No, I agree. That said, I also used 87 on my 250kmi 8psi turbo shitbox for years and it was fine with me because it was a $500 car and a gas savings

 

Ohh gotcha. Sorry I didn't realize what you saying.

Ohh yeah, send it in a shitbox.

 

So it’s an official hard no for 85 & 86 octane on a 11:1 15psi boosted DI motor- who knew?

I’m glad common sense still exists

Lots of good info here.

While we’re at it, what about E85?

And what about nonethanol fuel?

This thread is going to save a motor or 2

 

The manual specifically says to use fuel with up to 15% ethanol with a diagram showing "E30", "E50", and "E85" crossed out. E85 is right out. Non-ethanol fuel — of at least 87AKI — might net you slightly better fuel economy due to gasoline having more energy per unit mass than ethanol, though my experience using it in other cars is that it's sufficiently more expensive that it doesn't end up working out.

 

What if the truck is an automatic?

 

Why would that make any difference? More energy per unit mass means the engine will produce more power using the same amount of air and fuel. As long as you're driving the same way — accelerating at the rate you're accustomed to — you'll burn less fuel because the fuel has more energy in it. A gallon of pure gasoline will take you further than a gallon of ethanol in an engine that can burn either.

 

LOL - That was a joke...

 

That is hilarious you are basing your "data" and "science" on a report from 1987. Yep got it engines and technology haven't changed one bit. From 1987 there is also probably a report that smoking isn't that bad for you either.

I will continue to wait for the actual data because it is just like mentioned above. Oil change interval, what psi to run and the list goes on.

 

Your personal anecdote is worse than useless, it’s misleading and counter to all manufacturer, government, and third-party testing conclusions. I presented something other than a story.

Read the SAE paper, its conclusions about octane at altitude with EFI engines largely still apply to modern engines and they’re in line with all advice from modern authorities on the subject.

Or are you one of those guys who’s just blindly going to dismiss anything counter to his personal narrative? Because from here, you seem like one of those people.

 

Yep one of those people that lives by one of Mark Twains famous quotes, research it. Good bye, go name call someone else.