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Discussion Starter · #1 ·
Has anyone experienced any knocking from running regular unleaded in their 5.7?
Thanks, Tom-O:ts:
 

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Midgrade or premium is suggested in the owners manual! I have 1600 miles on my Crewmax and only run midgrade. Truck runs great!:)
 

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Midgrade or premium is suggested in the owners manual! I have 1600 miles on my Crewmax and only run midgrade. Truck runs great!:)
What owner manual are you looking at? The manual specificaly says 87 or better. Last time I checked, 87 is not considered mid grade. Nobody on this forum so far has benefited from putting anything higher than 87 in the truck = no knocks, pings, added MPG or anything else.

Don't waste your money, just stick with 87.
 

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87 octane is recommended in the owners manual. This link may work, may not. Octane rating - Wikipedia, the free encyclopedia. Check out the information here and it should clear up the octane mystery. Octane rating has nothing to do with combustability of fuel for spark ignition internal combustion engines but rather is a rating system designed to identify the fuel's ability to resist predetonation (pinging, knocking, running on). That said, 87 octane has the same energy release per detonation as 93 octane.
 

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I have only used 87 octane in all of my vehicles, including the Tundra and my motorhome. Never ever had a problem. Paying the higher price for the higher grades only goes into the pockets of the greedy oil company CEO's....doesn't do a thing to make my Tundra run any better.
 

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Been running 87 octane in my Tundra since day one and it runs great.
 

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In response to COOPER S, Midgrade in Colorado is 87. And I'm sure I'm looking at the same manual as you! Thanks!
 

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87 here... no problems... slight gas mileage difference when running the higher octane but otherwise the same... slight meaning <1mpg... not enought to justify spending 5 more bucks
 

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The one thing that I have read about different types of gas is always try to stick to "teir 1" gas. It can be 87 as long as it is "teir 1", which I believe is just a standard to ensure quality gas, correct me if I am wrong please.


Zack
 

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87 octane is recommended in the owners manual. This link may work, may not. Octane rating - Wikipedia, the free encyclopedia. Check out the information here and it should clear up the octane mystery. Octane rating has nothing to do with combustability of fuel for spark ignition internal combustion engines but rather is a rating system designed to identify the fuel's ability to resist predetonation (pinging, knocking, running on). That said, 87 octane has the same energy release per detonation as 93 octane.
I don't know if everyone read this post, but a few that posted after should read it.

There is only one thing wrong with what he says. (The octane rating has nothing to do with the combustibility of the fuel), which is wrong, as he states later, (the octane rating is a system to identify the fuel's ability to resist pre-detonation).

Which is the same thing just stated different as the resistance to combustibility prevents detonation.

Basically 87 octane will ignite faster than 92 octane. For low compression engines you want to use a low octane fuel, for high compression engines you want to use a high octane.

If you use a high octane gas on a low compression engine (like the tundra) you are just hurting your performance! So don't be stupid, just run 87 only, unless you do some engine mod's or your environment causes and you get detonation there is no need to run anything higher.

As for the regular mid and premium grades they are different state to state depending on the additives most states are; 87 89 91, Oregon is 87 89 92, and I have seen some 85 and 90 octane around.

And for the people who don't know what detonation is, it is your fuel exploading before the spark ignites.
 

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Your engine shouldn't knock with 87 as the knock sensor will pull timing as necessary to prevent knock. However, if the computer is pulling timing you are giving up ultimate power and economy. The computer will retard timing instantly as knock is detected. It could take much longer to advance it back to optimum. It may be as little as a start cycle or as much as a couple tankfulls- Only a factory engineer could tell you the exact learning period. I drive in 90 degree weather at sea level and I drive hard. I want ALL the power my engine will give. I'll use 93. At 10 cents per gal difference(here) that's only $2.50 per tank. Some people pay hundreds of dollars for a "chip" (almost $1000 for unichip) to get advanced timing when it may already be built into the truck.

BTW- the same light petroleum distillates (toulene, xylene, benzene, heptane etc) that boost octane in gasoline blends are also the ones that are solvents that keep your fuel system(esp injectors) clean.

If you use 87 and are satisfied-great.
87 octane is cheaper and adequate
93 octane is costlier and better
run what you want.
Rumbler
 

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Timing just controls when the spark goes off, if you gas is igniting before the spark goes off the engine can't control that...

The only thing you are successfully doing by using 93 octane is making it harder for the spark plug to ignite your gas.

So I disagree 93 is not better...


Your engine shouldn't knock with 87 as the knock sensor will pull timing as necessary to prevent knock. However, if the computer is pulling timing you are giving up ultimate power and economy. The computer will retard timing instantly as knock is detected. It could take much longer to advance it back to optimum. It may be as little as a start cycle or as much as a couple tankfulls- Only a factory engineer could tell you the exact learning period. I drive in 90 degree weather at sea level and I drive hard. I want ALL the power my engine will give. I'll use 93. At 10 cents per gal difference(here) that's only $2.50 per tank. Some people pay hundreds of dollars for a "chip" (almost $1000 for unichip) to get advanced timing when it may already be built into the truck.

BTW- the same light petroleum distillates (toulene, xylene, benzene, heptane etc) that boost octane in gasoline blends are also the ones that are solvents that keep your fuel system(esp injectors) clean.

If you use 87 and are satisfied-great.
87 octane is cheaper and adequate
93 octane is costlier and better
run what you want.
Rumbler
 

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If the vehicle doesn't knock with the cheap stuff,
Where do I get some of the "Cheap Stuff"? Back when I was in High School I could drive my Chevy all WEEKEND on $2.00............
 

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Timing just controls when the spark goes off, if you gas is igniting before the spark goes off the engine can't control that...right, and lower octane fuels tend to combust from compression.

The only thing you are successfully doing by using 93 octane is making it harder for the spark plug to ignite your gas...no, the spark will ignite the fuels the same, the 93 octane will allow for full compression, may advance the timing, may increase power, and may increase fuel mileage.

So I disagree 93 is not better...
See red text above...


I say "may" due to other reports of folks on here that have said they tried higher octane with no noticable gains. I do not believe they ran multiple tanks of higher octane back to back.

When I do it, starting soon, I will be running 5 to 10 tanks of 91 octane and will post my results. I have ran nothing but 87 in my Tundra from the start.
 

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Discussion Starter · #20 ·
Thanks Rumbler for the link... just
what I was looking for.:tu:

Tom-O
 
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