Running higher than recommended octane fuel
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No benefit and might be a detriment - one of my brothers always ran 93 in an unmodified 87 engine and got a lot of carbon build up in the cylinders.
From what I know it will not in any way harm an engine to run higher octane than needed. The only harm that will come is to your wallet for the more expensive fuel. Octane is there to keep the gas from pre-detonating in high compression engines. The engines in your typical vehicle dont need high octane unless specified in the owners manual.
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My Owner's Manual states 87 or higher. If this is the case, i see no issue.
Price. You pay more for it, and in an engine that doesn't need it, and is not designed for it, you see zero benefit. Personally, I'd rather save the extra money for something worthwhile.
Originally Posted By: ArazelEternal
Octane is there to keep the gas from pre-detonating in high compression engines. T
Here we go with that pre-detonation thing again.
I see a number of members using the term "pre-detonation" when referring to pre-igniton or detonation.
Pre-ignition is what happens in an internal combustion engine when fuel is ignited by a hot spot prior to the desired ignition point, resulting in higher than normal combustion pressures.
Detonation in an internal combustion engine is when the fuel explodes rather than burns. The technical definition of an an explosion is when the burn front exceeds the speed of sound. The sound you hear when an engine detonates is the "sonic boom" generated by the supersonic flame front. This also results in extremely high combustion pressures.
Pre-detonation is what happens in an atomic weapon if the sub-critical fuel masses are exposed to stray neutrons and undergo spontaneous fission, destroying the fuel before it can be taken super-critical. Needles to say, but I'm going to say it anyway, this is not what is happening in your engine!
Ed
Octane is there to keep the gas from pre-detonating in high compression engines. T
Here we go with that pre-detonation thing again.
I see a number of members using the term "pre-detonation" when referring to pre-igniton or detonation.
Pre-ignition is what happens in an internal combustion engine when fuel is ignited by a hot spot prior to the desired ignition point, resulting in higher than normal combustion pressures.
Detonation in an internal combustion engine is when the fuel explodes rather than burns. The technical definition of an an explosion is when the burn front exceeds the speed of sound. The sound you hear when an engine detonates is the "sonic boom" generated by the supersonic flame front. This also results in extremely high combustion pressures.
Pre-detonation is what happens in an atomic weapon if the sub-critical fuel masses are exposed to stray neutrons and undergo spontaneous fission, destroying the fuel before it can be taken super-critical. Needles to say, but I'm going to say it anyway, this is not what is happening in your engine!
Ed
One thing to consider when buying premium gas is where you buy it - a small independent gas station, or a high volume corporate owned chain store.
The premium at the small stations can sit for weeks, even months giving it a higher chance of phase separation or contamination.
Small independent gas stations will sometimes do sketchy stuff like order a full load of 87, then when the driver tries to unload it won't fit and the owner will ask them to dump whatever doesn't fit into the premium tank.
The premium at the small stations can sit for weeks, even months giving it a higher chance of phase separation or contamination.
Small independent gas stations will sometimes do sketchy stuff like order a full load of 87, then when the driver tries to unload it won't fit and the owner will ask them to dump whatever doesn't fit into the premium tank.
Originally Posted By: SOHCman
There is a big difference in the answer if you are talking about ethanol laced premium or ethanol free Premium. There is more BTU in ethanol free = good.
I doubt they spike the gasoline with ethanol where the OP is from.
There is a big difference in the answer if you are talking about ethanol laced premium or ethanol free Premium. There is more BTU in ethanol free = good.
I doubt they spike the gasoline with ethanol where the OP is from.
Originally Posted By: working_title
One thing to consider when buying premium gas is where you buy it - a small independent gas station, or a high volume corporate owned chain store.
The premium at the small stations can sit for weeks, even months giving it a higher chance of phase separation or contamination.
Small independent gas stations will sometimes do sketchy stuff like order a full load of 87, then when the driver tries to unload it won't fit and the owner will ask them to dump whatever doesn't fit into the premium tank.
I never even thought about this, I used to buy premium from a small place regularly.
One thing to consider when buying premium gas is where you buy it - a small independent gas station, or a high volume corporate owned chain store.
The premium at the small stations can sit for weeks, even months giving it a higher chance of phase separation or contamination.
Small independent gas stations will sometimes do sketchy stuff like order a full load of 87, then when the driver tries to unload it won't fit and the owner will ask them to dump whatever doesn't fit into the premium tank.
I never even thought about this, I used to buy premium from a small place regularly.
Originally Posted By: Nissan101
Are there any disadvantages of running fuel of higher octane, when the manufacture recommends a lower octane.
Thank you.
Dont say its the price. Any other disadvantages?
Here are three current threads running in the "Fuel" section.
https://www.bobistheoilguy.com/forums/ub...cta#Post4581474
https://www.bobistheoilguy.com/forums/ub...m_w#Post4788576
https://www.bobistheoilguy.com/forums/ub...is?#Post4714846
Are there any disadvantages of running fuel of higher octane, when the manufacture recommends a lower octane.
Thank you.
Dont say its the price. Any other disadvantages?
Here are three current threads running in the "Fuel" section.
https://www.bobistheoilguy.com/forums/ub...cta#Post4581474
https://www.bobistheoilguy.com/forums/ub...m_w#Post4788576
https://www.bobistheoilguy.com/forums/ub...is?#Post4714846
In the past, I've always found that using a higher octane gas than specified/required was a complete waste. After buying a new car with GDI engine, I ran mpg tests using regular (87 oct) and premium (91 oct) and found essentially no difference. At 20,000 miles, however, I repeated the experiment and was shocked to find that premium gas improved the gas mileage by 2mpg and the car had noticeably more zip. I concluded that carbon buildup was responsible for the change and that the ECM was retarding the timing/spark when the lower octane gas was used.
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Originally Posted By: edhackett
Pre-detonation is what happens in an atomic weapon if the sub-critical fuel masses are exposed to stray neutrons and undergo spontaneous fission, destroying the fuel before it can be taken super-critical. Needles to say, but I'm going to say it anyway, this is not what is happening in your engine!
Ed
Thanks for that!
Pre-detonation is what happens in an atomic weapon if the sub-critical fuel masses are exposed to stray neutrons and undergo spontaneous fission, destroying the fuel before it can be taken super-critical. Needles to say, but I'm going to say it anyway, this is not what is happening in your engine!
Ed
Thanks for that!
Some engines can increase power output on 91-93 octane. Others can’t. Generally HIGH compression and turbo engines can take advantage of the higher octane to advance timing and lean the mixture a bit vs running on 87.
My fusion doesn’t care. I tested a tank of 93 on the interstate, ran it to empty, and made the trip back with a tank of 87. Mileage was identical. So I run 87
My fusion doesn’t care. I tested a tank of 93 on the interstate, ran it to empty, and made the trip back with a tank of 87. Mileage was identical. So I run 87
Why is this in the PCMO forum?
If there's nothing wrong with your engine, higher octane is a waste of money. The only exception is certain models that are specifically designed for additional output on higher octane fuel. For example, the owner's manual for the 2nd gen Tacoma 4.0 V6 states clearly that higher octane will produce higher performance. But it will run just fine on regular 87 octane.
If you have carbon buildup on the combustion chamber or piston crowns, or some other reason why the engine is experiencing detonation or pre-ignition, higher octane will likely help but this is just a band-aid and not a real solution.
If you have carbon buildup on the combustion chamber or piston crowns, or some other reason why the engine is experiencing detonation or pre-ignition, higher octane will likely help but this is just a band-aid and not a real solution.
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