Higher octane for better mileage?

[14Corolla]

I remember my auto shop teacher, told us about octane.
He illustrated it by;
Stood at an open door. He hit the door with his hand. It pushed open more.
He said that is low octane. It hits the piston to make it move.
He then put his hand to the door and pushed. He said that is high octane fuel. Less hitting the door to make it move.
Basically.....low octane explodes more....high octane burns more...

This is not an attempt to explain methanol with it's lack of efficiency in an engine.

[14Corolla]

I just filled up with regular, E0, 85 octane. There is a definite world of difference here. Now bear in mind that it still has the 10% ethanol from three gallons in there. This car is performing completely different now. No more thoughts of; well got to get used to the transmission, or the extended idle resulting a little rough...no more of that stuff. I stepped on the gas and it surprised me. I'm just nudging the pedal now. Lots more power.
This tank I filled up. I got my best with ethanol. Came to 38.1 mpg. That's with a 60 mile freeway trip. The computer barely came up on 40 mpg...stayed below on the graph.
Today with this tank. Drove to work. Yup, I worked today. That computer went up to 50 mpg for the tank. Came back down and is sitting right at 40 now. This is a whole different world than the E10 ethanol. I never saw 40 there.
I have no idea what kind of mileage my car is going to settle on? I'm overjoyed with this regular E0. This car is doing far beyond my expectations. Still got some to do to increase mileage.
My car seems to be overjoyed. Gave it the 'hard stuff'....the Saki.

[benlovesgoddess]

A lad at work says one of the supermarket chains expensive brands of petrol (there are no more than two types of each petrol and diesel at UK pumps, one usually about 20% dearer) is 99 octane, best in our market, with the Shell top line being 98 octane. I am tempted to test the Tesco one next...filled up on another supermarket chains regular when I picked up the car, is it was a minute from the Toyota dealers.

A quick fact check on Google says that in fact both Tesco and Shells top line are 99, while our regular unleaded is 95, and other brands top line (super unleaded) is 97.
I have no experience with petrol, but I seem to recall with diesel, paying 20% more to get a 10% improvement in economy. The sales pitch for premium fuel was that it also cleaned and looked after your engine, so every few months you'd feel like giving the car a treat...

[14Corolla]

Originally Posted by 14Corolla

This is not an attempt to explain methanol with it's lack of efficiency in an engine.

That was a typo. Just noticed. I meant: ethanol. Not methanol.

The higher octane ratings in the UK are interesting. Is it about the same in Europe? I remember being taught that kerosene is very high octane.
Interesting the two brands. Was leaving out BP, just an oversight?
We've had problems with Diesel here. When it gets cold. It will gell. Plug up the filters. Plug up fuel lines. Out number 2 diesel is supposed to be good to 20 below zero f. That's about the same as -20C. It wouldn't even come close. In single digits 'f' it was doing that. I think they were cheating. Now they claim better and we still don't trust them.
That on the diesel leads me to think that maybe they have been cheating on the ethanol. More than stated? The difference without ethanol is impressive to me.

[Draigflag]

The RON or Octane numbers are different between the US and Europe so are not directly comparable. The fuels are very different though, we have more additives and less sulphur in ours, hence why we only need to change our oil once every couple of years. We also use winter blend diesel as you guys do, to stop it gelling, and recently I looked at my figures and noticed about a 5-10% drop in economy using it. Can't help with your other questions sorry.

[14Corolla]

Interesting on the winter blend diesel. Ours is supposed to be better. Called Number 1. Remember what I stated on Number 2. They claim our Number 2 is now 15 ppm Sulfur. My truck gets it's oil changed at around 650 hours. Use hours on trucks because they also sit and work. That's pretty normal for trucks here. Works out to a couple, maybe three times a year.
On petrol. I do find it interesting. Toyota has me using Synthetic Oil. Change it at 10,000 miles. No filter change in between. It's very light oil. 0W-20 weight. I trust Toyota's engineers.
Besides... changing oil every 2500 miles is much more hassle.

I enjoy reading the comparisons and differences. Don't have to worry about me using it to create a conflict of sorts. There are too many people in this country who are a conflict looking for a place to happen. Gee.... I even talk on a gun forum where we talk politics. It is a special forum. They kick troublemakers out. We still disagree and kid each other. The moderators have a wise eye for the troublemakers.

[Draigflag]

It's refreshing to chat to someone open minded like you my friend. Just last year I questioned the obsessive oil changes in the US as at the time, I didn't understand why the same cars here would require such little oil. This one guy sent a barrage of abuse, insulted me and my car and basically said he wanted to run me over in his enormous truck. Still makes me smirk today!

I'm not sure about the big semi trucks here, I should imagine they go by hours too, although I read on a manufacturers truck website that they do 60,000 between oil changes. The biggest interval I've seen for a light passenger vehicle is probably about 30,000 miles, on average it's around 15,000 to 20,000 with the modern synthetics, but it does recommend sooner if you've been "racing" or driving in dusty environments. I try not to talk guns here, it's a sensitive issue in the states. I mentioned it once and got shut down, I guess we should stay on topic

[14Corolla]

That sounds about normal for people in this country these days. Looking for anything to run off in a tangent and throw a fit. I call them: "Terrible Two's Fits". No actual communication on anything. Nothing constructive.
That's why I spend much time online talking. Just for some intelligent input and interaction.
Can't even talk guns on many gun forums. They're awful. Same reason as above. That one I mentioned is special. Can't see a reason to talk them here.
I do sincerely appreciate the info. Different practices and such. Again....I find it interesting. Just makes me want to find out more.

[trollbait]

Originally Posted by 14Corolla

That was a typo. Just noticed. I meant: ethanol. Not methanol.

The higher octane ratings in the UK are interesting. Is it about the same in Europe? I remember being taught that kerosene is very high octane.
Interesting the two brands. Was leaving out BP, just an oversight?
We've had problems with Diesel here. When it gets cold. It will gell. Plug up the filters. Plug up fuel lines. Out number 2 diesel is supposed to be good to 20 below zero f. That's about the same as -20C. It wouldn't even come close. In single digits 'f' it was doing that. I think they were cheating. Now they claim better and we still don't trust them.
That on the diesel leads me to think that maybe they have been cheating on the ethanol. More than stated? The difference without ethanol is impressive to me.

The rating on the pump in the US and Canada is the gasoline's AKI; an average of RON and MON. A few other places also use AKI, but most of the world reports RON, which is a higher value than MON, and thus higher than AKI. US regular has a RON of around 91 to 92.

We should switch to RON and increase the regular octane rating. RON is the more important number for when it comes to designing modern, fuel injected engines, this should reduce the R&D costs for new models. The higher octane will allow higher compression engines, which should be more thermally efficient.
https://en.wikipedia.org/wiki/Octane_rating

I think you are confusing kerosene's cetane number for octane. That is an inverse measurement of what octane measures. The higher the value, to more likely it will ignite when compressed, which is what you want for a diesel. Kerosene and diesel octane ratings are very low.

Motor oil change intervals have gotten longer for various reasons. The oil itself, and the additives, have gotten better. It is possible for a 'synthetic' oil on a store shelf in the US to have no actual synthetic, group IV oils in it, and just be well refined group III ones.

Then the engines and their manufacturer have gotten better. Tighter clearances in the parts means less fuel and other contaminates get into the oil. Plus, the fuel has gotten cleaner. Lower sulfur in the fuel means longer oil life. The US is planned to start moving to ultra low sulfur gasoline in the next year or so.

[Skydaver]

A fuelly noob pipes up here. I just sold a 2002 Maxima, 6 spd manual, that I bought new. I put 145,000 miles on it, and kept track of my mileage with an Excel spread sheet.

Just before I sold it, I decided to try an experiment. I ran 2500 miles on regular (87? 89?, whatever) octane (Nissan specifies premium.)

Now, the previous 2500 miles on premium, I wasn't quite as mindful about fuel economy, and it was a different season, but ...

I got 1.3 mpg better on regular.

On regular, I did get a very slight knock on a low rate acceleration that was quickly stopped by the ECM. Heavy acceleration had no knock at all.

So, IMO, use the cheapest fuel you can. Once in awhile, run a tank of a name brand premium through, not for the extra octane, but for the detergent mix that it has.