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I use premium it is not that much more expensive and a lot cheaper than adding octane booster. Which doesn't usually amount to much of an octane boost unless you spend a whole lot more.

With the high gas prices it is cheaper (as a percentage) to run premium than it used to be.

Ex Premium - $4.20 reg $4.00 gal
4.00 / 4.20 = 4.76% higher to run premium

When gas prices were "reasonable"

premium $2.10 regular - $1.90
1.90 / 2.10 = 9.047% more to run premium.

So as a percentage the cost to run premium vs regular has actually decreased.

Still about $3.00 more a fill up though...but I do get slightly better gas mileage so that offsets it too. Based on a 4 tank fill up comparison, just over 1 mpg better. 16 gallons x 1 mpg = 16 extra miles, which is .76 of a gallon for me (21 mpg). .76 x 4.20 = $3.20 savings, which completely offsets the increased cost.

JMO
 
I personally use Premium. If you happen to have a Liberty gas station near you, their Premium price is comparable to the Mid-grade of the others (BP, Sunoco, etc.).

I have a 2010, which uses the newer Dual VVT-i technology. According to Wikipedia, using 91 octane fuel provides a 20 hp boost over using regular. I personally find it hard to believe, but since the difference in price is negligible, and it personally feels faster on my butt... I go for premium all the time. The fact that some find it helps in fuel economy only solidifies my choice.

I'm sure that if I did a blind "taste test" where someone else was filling up my FJ and I didn't know which tanks were premium and which were regular though, the butt dyno would probably provide mixed results. But for me, the price difference is small enough to just take the plunge and hope for the best.
 
In my 07, I alternate regular and premium every other tank but would be running regular all the time if I didn't believe the hype about 07-09s needing premium.
 
All other things being equal, higher octane gives better performance if the motor can take advantage of it. There are other factors to consider that are difficult or impossible to account for. Ethanol content lowers performance, no matter the octane rating. Stations don't post ethanol content. They might say 'at least' 10% or something else, but you never know the actual percentage. If you find a station that uses no ethanol additive, USE IT! You will be happy with performance if you romp on it. You will be happy with mpg if you have a light foot.
 
I've heard through the grapevine that Shell uses less ethanol and I have had some all time high mileage fill ups from Shell. All gas now has ethanol as well, just differing amounts.
 
I use whatever is the lowest octane rating available. Usually 86, sometimes 85. I have never read any convincing scientific evidence that running premium gas gives improved mileage in a car that's designed for running regular.

The only exception would be if I knew there was ethanol free gas available - I'd use that one.
 
I use whatever is the lowest octane rating available. Usually 86, sometimes 85. I have never read any convincing scientific evidence that running premium gas gives improved mileage in a car that's designed for running regular.

The only exception would be if I knew there was ethanol free gas available - I'd use that one.
But a car designed to run on "regular" is different than a car designed and tuned to run on 91. For sure there is absolutely no advantage to running premium in an engine designed for 87 octane. Just a waste of money.

But in an engine that is designed to run on 91 for optimal power and torque, there is a difference. The VVT on the FJ engine will retard timing as needed for lower octane but it will be at the sacrifice of optimal performance. Optimal performance is with the timing advanced as Toyota designed and tuned this engine, which is achieved with higher octane fuel.

Granted in my 8 fill up comparison there are known variables and unknown variables. A big unknown is the content of ethanol in the 87 octane compared to the content of ethanol in the 91.
 
Ethanol content lowers performance, no matter the octane rating.
This part is not true. Ethanol actually increases the effective octane rating of the fuel and gives higher performance. Flex-fuel vehicles get more HP and torquer using E85 vs. normal E10. But the fuel has a lower energy density, so you get lower MPG using it. Some engines, especially older engines, may run better off pure gasoline than E10, but this is for other reasons.

And while stations don't post ethanol content, unless you are getting ethanol-free gas, all pretty much all commercial gas is E10. Depending on the specific blend it may be E8 or E9, but ethanol is cheaper and raises the octane rating, so refineries use as much as they can.

And for those using premium, that is almost guaranteed to be E10, as ethanol is an octane booster.
 
Using premium grades of gas on pre 2010 FJ's will give you better performance but in the new 2010 and up engine with dual; VVTI there is no difference, the cheapest and the most expensive gas will still give you the same power.

In my 2008 FJ I used to fill 97 Octane bit now in the 2010 I am using 87.

The pre 2010 FJ had two sets of power / torgue figures in the book, one for Regular gas and one for Premium Gas but not anymore in the newer ones !
 
Using premium grades of gas on pre 2010 FJ's will give you better performance but in the new 2010 and up engine with dual; VVTI there is no difference, the cheapest and the most expensive gas will still give you the same power.

In my 2008 FJ I used to fill 97 Octane bit now in the 2010 I am using 87.

The pre 2010 FJ had two sets of power / torgue figures in the book, one for Regular gas and one for Premium Gas but not anymore in the newer ones !
From Wiki : "An updated version of this engine features Dual VVT-i, increasing output to 254 hp (189 kW) and 270 lb·ft (366 N·m) on 87 octane and 285 hp (213 kW) and 289 lb·ft (392 N·m) on 91 octane. "

For whatever its worth..:cheers:
 
i had asked the saleman about the higher octane and he said any octane would work. mine is a 08 bought brand new and used the higher octane for a few tank fulls, but the price was bitting me. so i tried the cheaper stuff and never felt any difference. been using 87 ever since and besides using some injector cleaner form time to time, i never had any problems.
 
OUF ! me 98 octane !
 
With a SC, you should be running the highest octane. The higher pressures can (and will) ping and knock with lower quality. You ought to try some Toulene and have some fun! I used to put it in my turbo cars and crank the timing and boost up!! Mucho Funo!!


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in my 07, it makes no noticeable difference with mpg, power, or knocking what octane gas I use. I am always at elevation of 4500-10000ft if this matters. I have read that elevation makes up for octane?
 
Higher elevation has less O2, so the car technically wouldn't need the higher octane. But in reality, our engine works harder because of the thinner air. So even at altitude, higher compression engines still need the higher octane.


Sent from my Autoguide iPhone app
 
Higher elevation has less O2, so the car technically wouldn't need the higher octane. But in reality, our engine works harder because of the thinner air. So even at altitude, higher compression engines still need the higher octane.


Sent from my Autoguide iPhone app
That makes sense so we run more rich as well? Less air/more fuel I assume but the computer must compensate?
 
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