Interesting fuel....

[14Corolla]

Just got 41.1mpg again. There was reason to drive down the mileage a little.
Right now I'm thinking I'm stupid to play around with any other fuel. This is good stuff. 100% Regular 85 octane, no ethanol. This is a 'corporate owned store'. They might have more influence (or choice?) to get good fuel.

[trollbait]

You're lucky. Most of the population only has E10 as an option. The ethanol is the big factor.

[freeatlast]

Higher octane does not give better MPG. Do a google search on the subject. Higher octane does not have any more BTU's than lower octane. Octane is an anti knock additive not a BTU additive.

As for 85 octane that is below what the manufacture recommends for these vehicles. 87 is the lowest that should ever be used or you could suffer head gasket problems from poor detonation.

Pure gas will always give better MPG than an Ethanol blend You can get 10 to 15 percent better MPG with pure gas. There is absolutely no need to mix different octane ratings.

[freeatlast]

Originally Posted by 14Corolla

There is no such thing as ethanol free mid grade.
All mid grade has ethanol. I think it's about 89 octane.
The regular with ethanol is 87 octane.
The regular without ethanol is 85 octane.

That is not true unless you live in an area that by law requires that. I run 87 octane pure gas/ ethanol free gas.

[JockoT]

I thought that modern cars have a knock detector that checks for the onset of knocking and adjusts the timing accordingly? I may be mistaken, but that is my belief regarding my Honda Jazz. And if the fuel allows a more advanced ignition setting that is supposed to give better performance.
Feel free to slap me down if I am wrong.

[JockoT]

Seemingly, here in the UK, all fuel is E5, unless a pump is clearly marked as E10 (max allowed in UK). Personally I have never seen an E10 pump here in Scotland.

[freeatlast]

Originally Posted by JockoT

I thought that modern cars have a knock detector that checks for the onset of knocking and adjusts the timing accordingly? I may be mistaken, but that is my belief regarding my Honda Jazz. And if the fuel allows a more advanced ignition setting that is supposed to give better performance.
Feel free to slap me down if I am wrong.

Yes they do have an anti knock sensor, but the sensor is not infinite. It is limited to what the lowest octane rating that the manufacturer recommends. That is why they warn you. They can only adjust the timing so far. Any octane below the recommended is taking a chance of internal knock with head gasket and/or head failure.

[JockoT]

Thanks. We only get 95 and 97 RON here in the UK.

[trollbait]

Originally Posted by JockoT

I thought that modern cars have a knock detector that checks for the onset of knocking and adjusts the timing accordingly? I may be mistaken, but that is my belief regarding my Honda Jazz. And if the fuel allows a more advanced ignition setting that is supposed to give better performance.
Feel free to slap me down if I am wrong.

Knock sensors aren't miracle workers. The system runs the most advanced ignition timing it can, but it can only advance so far. Without a higher compression ratio, using a higher than recommended octane isn't going to provide any performance or efficiency benefit. The cases in which that do exist usually involve cars in which the manufacture recommends a lower octane for sales purposes, but the engine was actually designed for higher.

Originally Posted by freeatlast

Higher octane does not give better MPG. Do a google search on the subject. Higher octane does not have any more BTU's than lower octane. Octane is an anti knock additive not a BTU additive.

As for 85 octane that is below what the manufacture recommends for these vehicles. 87 is the lowest that should ever be used or you could suffer head gasket problems from poor detonation.

Pure gas will always give better MPG than an Ethanol blend You can get 10 to 15 percent better MPG with pure gas. There is absolutely no need to mix different octane ratings.

A larger compression ratio can provide better performance and efficiency. So higher octane can improve fuel economy in an engine over lower, if that CR is high enough to take advantage of it.

Octane lower than 87 is available in areas of high elevation, because of the thinner air. Using it in a naturally aspirated engine in those locations isn't an issue. The engineers would have designed a safety buffer into the system if a car with 85 in its tank goes down to a lower elevation, or if the gas happens to age.

[14Corolla]

Originally Posted by freeatlast

Higher octane does not give better MPG. Do a google search on the subject. Higher octane does not have any more BTU's than lower octane. Octane is an anti knock additive not a BTU additive.

As for 85 octane that is below what the manufacture recommends for these vehicles. 87 is the lowest that should ever be used or you could suffer head gasket problems from poor detonation.

Pure gas will always give better MPG than an Ethanol blend You can get 10 to 15 percent better MPG with pure gas. There is absolutely no need to mix different octane ratings.

Octane is not an additive. Octane is the value of how well a liquid burns, rather than explodes. Nitro Glycerine is extremely low octane. Kerosene is very high octane.

You give absolutes that are completely irrelevant. You completely ignore why the octane is what it is. It is, because of elevation. At low elevation the octane is one thing. At higher elevation, they lower the octane to match the low elevation performance. This is decided by the refinery. My playing around with octane is trying to better match my octane to my elevation. That is all.
And yes, at stations in the large city here. I obtained better mileage by mixing premium and regular to up the octane on the regular. I consider doing it with different stations regular outside of that city. This stuff is doing pretty darn good for me now. It might just work out as playing around. ????