hello guys!!
so obviously gas prices are insane.
and many many many of you guys have mentioned previously that 91 octane is not needed
if you guys say so... why would toyota write in their manual that we do need 91 octane?

They didn't. What the manual says is:

Octane rating 87 or higher. For improved vehicle performance, the use of premium unleaded gasoline with an Octane Rating of 91 or higher is recommended.

Meaning the motor can take advantage of higher octane for more power, but your engine doesn't need it.

 

you have the v6 which has a really high compression ratio 10:1 i believe..it's good to feed it sum 91 to keep knocking down but the ECU shud pull enough timing to prevent knock if u use 87 though

 

exactly.
In fact, without the advanced power train controls (i.e. conventional CDI and mechanical timing from the 1980s), your engine would knock with 93 octane, under certain loads, given the compression ratio. Regardless of octane (as long as it's 87 or higher), the processor is monitoring the intake temp, mass flow rate, coolant temp, exhaust oxygen levels, etc. as well as a knock sensor. The timing and mixture are constantly adjusted in an effort to achieve the maximum performance under the conditions. Using a higher octane fuel (which is more resistant to pre-ignition due to high compression ratios and temperatures) allows the control unit to retune for higher performance. If you want "performance" then the higher octane will give you the most. If you are miserly, you'll also get more mpg -BUT, the increase in mpg has not been more than 2 or 3% for those of us who have actually compared, whereas the increase in fuel cost/gallon has remained over 5%, so you won't be doing your wallet any favors until the price goes up enough that regular is roughly 97% or so of the cost of premium.

 

hello guys!!
so obviously gas prices are insane.
and many many many of you guys have mentioned previously that 91 octane is not needed
if you guys say so... why would toyota write in their manual that we do need 91 octane?

:disappoin

 

I use both and I stick with regular. No noticeable change in MPG...plus regular saves in the wallet.

 

As stated 91 octane is "recomended" for optimal performance according to the user manual. I use 91 octane only when pulling my trailer. I will admit though I was not happy with 87 octane as I got more engine knock than I was happy with. My 04 Toyota Sienna has the same issues with engine knock at 87 octane. I still run 87 in the van though but have switched to 89 in the Tacoma. No more engine knock.

 

I filled up for the first time yesterday and I'm getting 19mpg because I like to baby it when it's new. It is a hell of a lot better than the 15 I was getting in my f150.

 

Don't let higher octane fool you. 87 octane actually burns hotter and makes more power as long as your engine doesn't have high compression. By no means is 10:1 considered high. The only advantage to higher octanes is the stability to not detonate under high comression. I have seen dyno tests with motorcycles with 10.5:1 compression that actually made more power with 87 than 92. The fuel industry has conditioned the public into thinking 92 octane (premium) is the best. I have found many times that you have to be closer to 11:1 to actually need 92 octane. So guys save your money and buy 87. If you have a knocking or detonation issue try another gas station. If you still knock then bump up to 89 and give it a shot. Don't think by spending that extra money you are doing you and your truck a favor.

 

I thought my answer was as clear cut as can be, why are the rest of you posting less than clear cut answers?

 

Yes Worthywads your answer was clear cut about what the manual says. I was explaining the theory behind it and how higher octane is less beneficial unless you have higher octane than a Tacoma.

 

alrighty i get it now
thanks alot hahahha
but more questions though
does it matter which gas station u go to?
i always go to 76. or shell.
but i see cheaper prices at ARCO or Valero
are those gas stations good too?

 

I like BP because it is not Arab oil. F)$% the arab oil companies. Exxon Mobil can especially go to hell.

 

I always use 91 octane, not even once have I used 87. Chevron 91 with Techron.IMO.:thumbup:

 

I always use 91 octane, not even once have I used 87. Chevron 91 with Techron.IMO.:thumbup:

haha.. yea, that'd be nice, but not everyone can afford that stufff. it's costing me about 60 bones to fill up on 87, on 91 it has to be about 70 bones a tank.. eep. kudos to you if you can afford that though

 

87 octane here, 21mpg on the highway. What works for one doesn't always work for the other...

 

Don't let higher octane fool you. 87 octane actually burns hotter and makes more power as long as your engine doesn't have high compression. By no means is 10:1 considered high. The only advantage to higher octanes is the stability to not detonate under high comression. I have seen dyno tests with motorcycles with 10.5:1 compression that actually made more power with 87 than 92. The fuel industry has conditioned the public into thinking 92 octane (premium) is the best. I have found many times that you have to be closer to 11:1 to actually need 92 octane. So guys save your money and buy 87. If you have a knocking or detonation issue try another gas station. If you still knock then bump up to 89 and give it a shot. Don't think by spending that extra money you are doing you and your truck a favor.

I disagree. Prior to the modern pwr train control modules, engine compression had been brought down (even below 8.5:1) in the 1970s, specifically to avoid knock w/ unleaded fuels burning leaner (which results in higher temps). Lead antiknock compounds (specifically tetraethyl lead compounds) were very effective at raising octane ratings cheaply. But the need for the catalytic converter was the death knell for lead which killed converters (and wasn't great for the atmosphere either). Higher octane fuels are, by definition, more knock resistant for the same temperature (the temp is related to cylinder temp, intake temp and very seriously by compression ratio). Higher compression ratios allow for higher output in the same displacement engine (basic Otto cycle characteristic). This is one reason why avgas is over 100 octane.

You can run higher compression ratios without knock at some loading conditions, but to accommodate a broad range of loads, temperatures, etc., you need to be able to rapidly retune ignition and valve timing as well as mixture. Hence, the modern control modules allow for higher mechanical compression ratios with 87 octane fuels. If you burn higher octane, the engine will retune to take advantage of it, as it is constantly edging toward the optimums which are on the verge of knock.

Some might say 87 burns "hotter" and extract more power to dollar -but that is only true if the engine is specifically tuned for 87, and is operating in that sweet spot just shy of knock. However, if the engine can be retuned for the sweetspot of a higher octane, the performance and efficiency will be greater with the higher octane. -Just not enough to justify the current cost difference of the fuel based on economy alone.

 

I like BP because it is not Arab oil. F)$% the arab oil companies. Exxon Mobil can especially go to hell.

I'm afraid that's an urban legend.
Crude is sold by exploration companies.
Refiners buy crude on the open market, they don't just refine their own crude.
Base stock gasoline is a commodity -it's traded on the commodity market just like pork bellies. The blending with additives and detergents is often proprietary with the major brands (though the smaller brands just sell what they buy on the market too - a generic, if you will).

So, you can't really pick a gasoline by the oil company name and have any idea where the crude came from.

Besides, the emails that have floated around suggesting boycotts of specific oil companies for the last 5 or 10 yrs are full of inaccuracies.
BP is the merger of a number of oil companies (including Amoco and Arco -both who are renowned for exploration in predominantly Arab countries -both Middle East and Asia), as is Conoco Phillips, ExxonMobil, ChevronTexaco, ...

Lastly- it's a fad to "dis" the "Arab" countries, even while some have been benign, and others have actually been our allies -at their own risk. It's a dangerous walk to the precipice of racism. I'm all for boycotting (or worse) countries/regimes that are our enemies or specifically aid or harbor terrorists, but you don't fire a weapon before you're sure of what you're aiming at or you risk injuring your friends or yourself.

 

Don't let higher octane fool you. 87 octane actually burns hotter and makes more power as long as your engine doesn't have high compression. By no means is 10:1 considered high. The only advantage to higher octanes is the stability to not detonate under high comression. I have seen dyno tests with motorcycles with 10.5:1 compression that actually made more power with 87 than 92. The fuel industry has conditioned the public into thinking 92 octane (premium) is the best. I have found many times that you have to be closer to 11:1 to actually need 92 octane. So guys save your money and buy 87. If you have a knocking or detonation issue try another gas station. If you still knock then bump up to 89 and give it a shot. Don't think by spending that extra money you are doing you and your truck a favor.

Most motorcycles have alot of cam overlap at lower rpm so the dynamic compression ratio is not as high as the static compression ratio. Once rpm builds the ratios become closer but with the higher rpm and less time for combustion detontation is not as much of an issue with proper ignition timing. Without computer controls we would all still be running 8.5 to 1 compression so 10 to 1 is not really low compression.

I think in Toyotas effort to squeeze out as much HP as possible they were relying on alot of ignition timing and 91 octane allowed this to obtain the horsepower numbers.

 

Well i run 87 all the time and my MPG stay around 20 MPG mark wih the AC on. So im very happy. Right about now i cant afford anything higher. A full tank cost about $50.00 or so give or take and last about a wk. So we are making it and besides much better than my 03 F-150 super creww i use to own which was about 15 MPG. Ouch.

 

I'm afraid that's an urban legend.
Crude is sold by exploration companies.
Refiners buy crude on the open market, they don't just refine their own crude.
Base stock gasoline is a commodity -it's traded on the commodity market just like pork bellies. The blending with additives and detergents is often proprietary with the major brands (though the smaller brands just sell what they buy on the market too - a generic, if you will).

So, you can't really pick a gasoline by the oil company name and have any idea where the crude came from.

Besides, the emails that have floated around suggesting boycotts of specific oil companies for the last 5 or 10 yrs are full of inaccuracies.
BP is the merger of a number of oil companies (including Amoco and Arco -both who are renowned for exploration in predominantly Arab countries -both Middle East and Asia), as is Conoco Phillips, ExxonMobil, ChevronTexaco, ...

This is so true especially in California. Gasoline is gasoline out here no matter who refines it. They all have to meet the same standards. So what's the difference between Shell, Chevron and Exxon? The additives that are put in the gasoline is what makes the brand. Up here in Northern California we have three major refineries but we have virtually all the major gas stations. Every gas station gets their fuel from one of the major refineries up here and the additives are put in after it leaves the refinery and before it goes into the tank at the local station. Basically that means that Shell refined gas could be in your local Costco tanks just without the additives.

 

haha.. yea, that'd be nice, but not everyone can afford that stufff. it's costing me about 60 bones to fill up on 87, on 91 it has to be about 70 bones a tank.. eep. kudos to you if you can afford that though

Yeap...I can't afford premium. Regular keeps my truck a going.

 

I'm afraid that's an urban legend.
Crude is sold by exploration companies.
Refiners buy crude on the open market, they don't just refine their own crude.
Base stock gasoline is a commodity -it's traded on the commodity market just like pork bellies. The blending with additives and detergents is often proprietary with the major brands (though the smaller brands just sell what they buy on the market too - a generic, if you will).

So, you can't really pick a gasoline by the oil company name and have any idea where the crude came from.

Besides, the emails that have floated around suggesting boycotts of specific oil companies for the last 5 or 10 yrs are full of inaccuracies.
BP is the merger of a number of oil companies (including Amoco and Arco -both who are renowned for exploration in predominantly Arab countries -both Middle East and Asia), as is Conoco Phillips, ExxonMobil, ChevronTexaco, ...

Lastly- it's a fad to "dis" the "Arab" countries, even while some have been benign, and others have actually been our allies -at their own risk. It's a dangerous walk to the precipice of racism. I'm all for boycotting (or worse) countries/regimes that are our enemies or specifically aid or harbor terrorists, but you don't fire a weapon before you're sure of what you're aiming at or you risk injuring your friends or yourself.

I saw something on the history channel about gas a while back. They showed the tankers from pretty much every brand of gasoline filling up at the same exact place. They said the only difference was the additives the companies added to their gas, so youre dead on about where the gas comes from.

 

I saw something on the history channel about gas a while back. They showed the tankers from pretty much every brand of gasoline filling up at the same exact place. They said the only difference was the additives the companies added to their gas, so youre dead on about where the gas comes from.

Don't get me wrong, I buy my fuel from majors, but only because they actually do research their additive packages, and their detergents are more state of the art and likely to be more consistent. But crude is crude and base stock gasoline is the same. The sign on the station has no indication as to what hole in the ground it went thru.

 

haha.. yea, that'd be nice, but not everyone can afford that stufff. it's costing me about 60 bones to fill up on 87, on 91 it has to be about 70 bones a tank.. eep. kudos to you if you can afford that though

Wow how much more is premium there? Around here, 89 is only 8-10 and 93 is 16-20 cents more than 87. If I'm filling up 15 gallons @ $3/gal bucks for 87 =$45. So cost me $46.20 with 89 or $47.40 w/ 93. Not much difference in price.

I have run all grades over 18 months, 87 is ok, run it if you can. It won't hurt the truck and its the cheapest. But for me, I get slight pinging on my steep hills and when mashing throttle, truck is smoother and runs better on 93, 89 good compromise.

 

Don't get me wrong, I buy my fuel from majors, but only because they actually do research their additive packages, and their detergents are more state of the art and likely to be more consistent. But crude is crude and base stock gasoline is the same. The sign on the station has no indication as to what hole in the ground it went thru.

Yeah me too. I only buy Shell, BP, Mobil, etc. Because I trust their detergents and additives. I would never buy gas from some noname store on a street corner even though it came from the same place Shell or the other namebrands comes from because they wont have the quality detergents the namebrands do.