Marvel mystery oil and similar fuel additives and octane?

Kql

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Jan 19, 2021
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I often hear people say anything with oil in it, which would include marvel mystery oil , gumout fuel system cleaner, lucas ect...lowers the fuel's octane, but I thought lower octane fuel is easier to ignite, not harder, would anything added to fuel (such as pale, light oil in some fuel additives not marketed as octane booster) . In theory wouldn't any oils in the fuel raise the octane, or am I getting this backwards?
Here's what I've noticed...low speed ping on my Rav4 is immediately and almost completely eliminated when I dump 16oz (full bottle) of 104+ injector pro in a full tank of fuel (16 gallons). I'm not exaggerating, with about 2 gallons left I'll pull up to the pump, dump the 16oz 104 injector pro in, fill the tank, start it, pull out and zero ignition ping.. I've done this 4 times over the last 6 months.. It lasts the entire tank. If I don't treat the next tank, the ping comes back.
 
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What year & engine RAV4? Sounds like your ignition timing is off.
Is your RAV4 an older one with the V6? Could be the knock sensors!
 
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What year & engine RAV4? Sounds like your ignition timing is off.
Is your RAV4 an older one with the V6? Could be the knock sensors!
I agree - something is wrong. No modern car should have noticable ping. Octane boosters only raise the octane of gasoline by 1 point and that is NOT meaning you go from 87 to 88 octane....you go from 87 to 87.1. That is all you get.
 
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The gas (and additive) that you just put in the tank will take a minute to reach the injectors. Under normal circumstances, you won't notice a difference as you pull away from the pump unless you run the engine a long time before leaving. I suspect the engine cooled slightly while you were pumping gas, this reduced engine temperature is which is why the engine did not ping as you drove away. But then, what do I know.
Modern cars will ping briefly in certain situations but it should be very mild and go away immediately. This is normal operation as the computer searches for optimal efficiency by adjusting the fuel and timing curves according to the circumstances.
 
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I often hear people say anything with oil in it, which would include marvel mystery oil , gumout fuel system cleaner, lucas ect...lowers the fuel's octane, but I thought lower octane fuel is easier to ignite, not harder, would anything added to fuel (such as pale, light oil in some fuel additives not marketed as octane booster) . In theory wouldn't any oils in the fuel raise the octane, or am I getting this backwards?
Here's what I've noticed...low speed ping on my Rav4 is immediately and almost completely eliminated when I dump 16oz (full bottle) of 104+ injector pro in a full tank of fuel (16 gallons). I'm not exaggerating, with about 2 gallons left I'll pull up to the pump, dump the 16oz 104 injector pro in, fill the tank, start it, pull out and zero ignition ping.. I've done this 4 times over the last 6 months.. It lasts the entire tank. If I don't treat the next tank, the ping comes back.
No, adding oil to the fuel will lower the octane rating. And "ease in ignition" as it relates to normal spark ignition has nothing to do with the octane rating. Higher octane fuel resists self-ignition better (knock) but that's not the same. If your vehicle is pinging on the proper fuel then as has already been mentioned there is something wrong with the engine.

If you learn what influences the octane rating you'll see why an oil lowers it.
 
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I agree - something is wrong. No modern car should have noticable ping. Octane boosters only raise the octane of gasoline by 1 point and that is NOT meaning you go from 87 to 88 octane....you go from 87 to 87.1. That is all you get.
“Should” ? plenty of modern cars have a light ping in some conditions.
 
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No, adding oil to the fuel will lower the octane rating. And "ease in ignition" as it relates to normal spark ignition has nothing to do with the octane rating. Higher octane fuel resists self-ignition better (knock) but that's not the same. If your vehicle is pinging on the proper fuel then as has already been mentioned there is something wrong with the engine.

If you learn what influences the octane rating you'll see why an oil lowers it.
Maybe this is oranges to apples, but... I heard some F1 teams designed their engines to burn a bit of oil in order to *increase* performance. The FIA viewed this as cheating and banned the practice. Looks like I am also confused about the relationship between fuel octane and burning oil.
 
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Maybe this is oranges to apples, but... I heard some F1 teams designed their engines to burn a bit of oil in order to *increase* performance. The FIA viewed this as cheating and banned the practice. Looks like I am also confused about the relationship between fuel octane and burning oil.
Yes you still get energy from combusting oil and you're not using fuel. But that isn't as if the oil has anything directly to do with the octane rating in this instance. They are just using it as an additional and unregulated source of energy.
 
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Maybe this is oranges to apples, but... I heard some F1 teams designed their engines to burn a bit of oil in order to *increase* performance. The FIA viewed this as cheating and banned the practice. Looks like I am also confused about the relationship between fuel octane and burning oil.
I think that was to get around fuel capacity limits, not increase performance per se.
 
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Yes you still get energy from combusting oil and you're not using fuel. But that isn't as if the oil has anything directly to do with the octane rating in this instance. They are just using it as an additional and unregulated source of energy.
"unregulated"?
Oil added to the fuel would still be metered by the fuel injection system and, asuming it burns, its contribution to combustion would be measured by the O2 sensor.
 
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