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I know that there after been other posts on this, BUT forget gas mileage, horsepower and all that. I want to know what will be the best gasoline octane for my engine (see signature). I want this truck to run for a long time. Which will be better for my engine 89 or 93? I know that the manual calls for 91 but we don't have it, and I really don't want to fill half 89, half 93. Thanks.

BTW- I do care about HP and mileage, but care more about the health of my engine.
 

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wvtaco said:
I know that the manual calls for 91 but we don't have it, and I really don't want to fill half 89, half 93.
QUOTE]

you just answered ur question right there...IMHO if the manual calls for 91 you should run 91...half and half....you said you want to make ur truck last long...and when the manual calls for 91 you should run 91 (half and half)
but i remember reading in a recent post that runing 87 is better because it burns cleaner...and 93 stays in ur engin or something like that and clog up things...not really sure...

i run 87...and i believe the manual called for 87...
 

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Run the minimum octane to meet the manufactureres recomendation. 91 is a cop out by Toyota for not recomending Premium. I normally tout running the 87 in the Tacomas but for your motor I will say that premium is the way to go especially since you shouldn't have to blend your own fuel at the pump(besides the fact that the octane factor is a set of averages, 50% 89+50% 93 does not= 90. Leave the blending to the petroleum chemist and pump a fuel that will work for your higher compression powerplant.

For the old Tacos 87 is king.
 

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Test the gas... Only put in a gallon or two. Should be about $10 bucks nowadays.... see if it pings, if it accelerates well. Try it for a day or 2. Then, try the other grade. Higher octane is meant for higher compression; it works in reverse in low compression motors. But computers on fuel systems are really advanced, and I would bet it adjusts for fuel combustion just fine. Plus, there are different ratings for fuel octane. Look back a week, and you will see the thread that explains 91 octane by one mouth is 87 by another. And enjoy.
 

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rojodiablo said:
Plus, there are different ratings for fuel octane. Look back a week, and you will see the thread that explains 91 octane by one mouth is 87 by another. And enjoy.
Different ratings yes, but what is posted at the pump is (R+M)/2. That is required by law in the states. And if it just says octane, they mean what is posted at the pump. If it says Research Octane, then it means the R in (R+M)/2. 87 octane and 91 Research Octane are the same thing.

87 octane and 91 octane are not the same thing.

The 2005 Tacomas with the 4.0 L V6 have a 10.0:1 compression ratio. 91 octane is recommended for maximum performance.
 

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wvtaco said:
I know that there after been other posts on this, BUT forget gas mileage, horsepower and all that. I want to know what will be the best gasoline octane for my engine (see signature). I want this truck to run for a long time. Which will be better for my engine 89 or 93? I know that the manual calls for 91 but we don't have it, and I really don't want to fill half 89, half 93. Thanks.

BTW- I do care about HP and mileage, but care more about the health of my engine.
At least for my truck i was running 87 or 91 for a long time till i decided to use 87 and i notice no gain in performance at all but i did notice a gain in my wallet. I personnaly beleave its not the grade of gas you run but its the type of gas you run. Ive always used cheveron for their so called techron additive. To me the more expensive the gas is the more refined it is so which makes it a cleaner gas for the engine.
 

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TRDUSA2002 said:
i notice no gain in performance at all but i did notice a gain in my wallet.
Its only about a dollar or two more per fill up. I know it adds up but compare it to the thousands we spend on mods its not something I would lose sleep over. IMHO.
 

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I definitely won't claim to be a fuel expert, but in many cases if your engine isn't built to utilize higher octane, at best you are wasting money. 91 in an engine built for 87 is pointless.

Higher octane is more resistant to combustion which is why it is commonly used in high compression engines. It's also why it is recommended for engines that have have pre-igniton or detontation issues.

The idea that higher octane is somehow "cleaner" is a also myth, unless the additive package is better.

Bottom line is octane has nothing directly to do with engine power.

This article is pretty good; it deals with aviation fuel as much as automotive fuel but the ideas and info are useful to understand octane and what it means for your engine:

Octane article
 

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Pete said:
I definitely won't claim to be a fuel expert, but in many cases if your engine isn't built to utilize higher octane, at best you are wasting money. 91 in an engine built for 87 is pointless.

Higher octane is more resistant to combustion which is why it is commonly used in high compression engines. It's also why it is recommended for engines that have have pre-igniton or detontation issues.

The idea that higher octane is somehow "cleaner" is a also myth, unless the additive package is better.

Bottom line is octane has nothing directly to do with engine power.

The article is pretty good; it deals with aviation fuel as much as automotive fuel but the ideas and info are useful to understand octane and what it means for your engine:

Octane article
Is engine is built for a higher octane. I agree with the minimal octane to meet performance requirements. he is relegated to using premium in most cases due to the 91 octane requirement from Toyota.
 

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Bryanccfshr said:
Is engine is built for a higher octane. I agree with the minimal octane to meet performance requirements. he is relegated to using premium in most cases due to the 91 octane requirement from Toyota.
Yeah, I would think for engine health as much as for performance, going by the book would be the way to go for the 4.0
 
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