Started using Premium gas for my 2006 SR5 Sport, 160K miles

I did a lot of testing a few years ago, and posted the results here. The comparison was between 87 and 91 octane California gas, Arizona gas, and ethanol free Mexican gas (87 octane). Highway driving 65-75 mph.

My Tacoma is a 2010 4-door, 4WD, V-6 automatic.

The results were no benefit to use 91 octane. The mpg was almost the same and 87 was a bit better... 18-19 mpg.

The big news was that ethanol-free, Pemex 87 octane gas (Mexico) gave the best mileage even with heavy loads and fast driving, 19-20 mpg.

 

How dare you bring actual test results into this discussion, why this is solely based on what we think!
Ignore him guys. But I really don’t have to say that do I ....

 

This is a very interesting thread. I've never seen a benefit to higher octane in any of my cars although I do have one vehicle with a high compression ratio which requires premium fuel. I've always been of the mindset it's a waste of $ unless you need it for the aforementioned benefits or safety on performance engines. Might have to give this a try, if I can get any MPG back that'd be awesome as mine SUCKS.

 

Interesting. On two long trips I had the opposite results, 89 mid grade octane Shell gave me a half mile or so per gallon more than Exon 87. One reason might be is our newer engine controls on 3rd gens are smarter and adjust the timing to the higher octane. Maybe. I trust the more scientific dyno test linked above better than our tests though.

 

I'm going to assume he means his truck felt supercharged cause if not, yikes.

 

Ohhh, yup, I definitely read that wrong, you're right.

 

Regular just doesn't cut it in my truck. I've been happy with 89 Mid Grade.

 

Doing your own testing is fine, but the odds of getting two identical drive cycles between two tanks of gas are impossible. Air, fuel, and tire temp are three things to consider. Modern cars deffently have the capability to "tune" the engine to current conditions by using MAP, MAS, barometric, upstream O2, intake air temp, and fuel temp sensors as well as others to keep the engine running at its optimum. I personally run 91 for the fact that I have torn down engins that have had shit gas ran through them their whole life and there is no denying that better gas keeps the internals of your engine cleaner.

 

I think it was the early gen FJ cruisers that had the same engine as the Taco but they specced 91 octane for them to show higher numbers. Go down to "Powertrain" on this wiki article.

 

The 1GR will advance the timing on higher octane fuel. This will undoubtedly free up a couple of ponies. The question is....can you actually feel that. I don't know.

The real advantage in using Premium is that SOME Top Tier fuels like Shell V-Power have addtional additives and detergents that go well beyond the mandated minimum. So in theory, your fuel system may stay cleaner over time....whether there's a performance gain or not

 

What are you smoking?

 

No matter what I put into it, it’s STILL the slowest vehicle on the Planet. Edit:

 

short of a race track, it's the only one that matters

 

2.7.....is what it is. But at least you'll be slow for 300+k miles.

 

The truck is rated to perform “better” with 91.

Spoken like a man who’s never driven an ‘89 ford ranger with the 100HP 2.3L 4 cylinder.

No speeding tickets as a teenager for me.

 

A month or so back, when gas was at about $1.50 per gallon around here, I switched to 93 octane for about four tanks full. I reset my trip meter and check my mileage every time I fill up. I usually see around 18 mpg.
When I was running the 93, the truck did seem to run better and had better throttle response. I saw maybe 1/2 mpg improvement, but it definitely 'felt' better. When gas prices started going back up, I switched back to 87. The mpg gain wasn't enough to justify the higher price, but I do agree that it felt like it ran better.
It could be placebo, but I don't think it was.
Run what you like. If it makes you happy and you can justify it to yourself, use it.

 

150... man that must be nice... i dont think i ever saw below 2 bucks here... back up to mid 2's now.

 

Higher octane rating gasoline does not burn slower, it resists ignition better.

Modern EFI systems constantly try to maximize efficiency and power by pushing the ignition timing advance until knock is detected and then backing off slightly, rinse, repeat... up to a point. When the IAM and fine learning knock correction are maxed out then it cannot advance the ignition timing any further without being reprogrammed to do so. This is typically not the case for most vehicles, especially now that all manufacturers are pushing the power/efficiency limit as much as they can without reliability issues.

In any engine with high mileage, unfavorable combustion chamber conditions like carbon deposits, feathered valve margins, etc that can be expected which could cause pre-ignition/knock to occur more easily so I'd guess that higher octane rating fuel could be more beneficial to older vehicles than the same lower milage vehicle. All that said, without ECU logging data that actually shows that this is happening in the same or very similar conditions, it's all butt dyno and everyone knows how accurate that can be.

That^^^

Surely they had a different ECU tune if engine hardware was identical

 

I owned an '06, and I currently own a '13. I distinctly remember my old owner's manual stating improved performance using 91 octane. That phrase is missing From my current owners manual, yet no changes have been made to the v6, that I am aware of. I did find this supporting what I remember from my old manual. Specifically, v6 horsepower, torque, compression ratio, and fuel requirement.

 

The tune was changed in at least the accel pedal to throttle plate relationship. Maybe other parts of the tune were changed to make 91 less of a benefit... Or they just dropped the verbage in the manual.