94 octane gasoline = quieter ICE

But we'll need to wait such a long time before that happens!

 

What brand, probably Chevron? More-n-likely ethanol-free then; did you check: the stickers on the pumps? Here in greater Van there's invariably a sticker on the 94 octane saying ethanol-free. The other octanes say "may contain up to 10% ethanol". Swing back and take a look?

Best tank we've ever had, I filled up at a Chevron up the coast, just regular, and it was miracle fuel. The liters per 100 km went down and stayed down, without even trying hard. More or less the best tank we ever had. Reading up a bit, I saw some reports that small town stations are more likely to have ethanol-free, the logistics of getting ethanol blend to out-of-the-way places sometimes make it impractical.

 

interesting, i've never heard that higher octane could quiet an engine. will be watching to see your next fill up, all the best!

 

So, your current tank is 50:50 of old gas of unknown origin:ethanol free 94 octane gas. In 2 months, when you fill half tank with 87 octane gas with ethanol, your tank will be 25:25:50 of old gas of unknown origin:ethanol free 94 octane gas:87 octane gas with ethanol. Not the same as your first tank.

 

Oh, I see. In that case, in 2 month you will be depleting most of current gas and replacing it this time with 87 octane with ethanol of known origin. As @Mendel Leisk eluded to you, it may be "ethanol free" that did the trick.

 

In any event, the thread title statement "94 octane gasoline = quieter ICE" is at best "yet to be proven" and at worst incorrect or misleading. Perhaps it should be re-phrased as a question...

 

might be helpful for others to try it and report back.

 

Computer controlled engines push the ignition timing to the edge of starting to knock for better efficiency. Knock sensors are actually microphones listening for those first knocks. If being at that point means a 'louder' engine, then a higher octane fuel that isn't near knocking at the engine's most advanced timing should be quiet in comparison.

I'm in the lack of ethanol being the reason camp. Not because of the ethanol directly, but because it is carrying water with it into the cylinder. 10% ethanol is really about 9.5% ethanol and 0.5% water, and it might even have more water than that.

 

Worth noting: it's my understanding that all grades of US gas are 10% ethanol, whereas up here it's 10% in regular, 0% in the station's highest octane, and the mid-grade is likely a mix of the other two, around 5%. Shell stations typically have a decal saying in effect:

Regular: 10%
Mid-grade: 5%
High-grade: 0%

And while they don't come right out and say how that comes to be, it seems plausable that mid-grade is just a mix.

Chevron, there's three pumps say "may contain up to 10%". Then an by itself pump, Chevron Supreme, octane 94, with the decal emphatically saying no ethanol, words to that effect.

I would just kill for some regular ethanol free. It's frustrating to have to pump Chevron Supreme, basically a higher octane, harder to ignite fuel, designed for sports cars with high compression engines, in order to dodge ethanol.

 

Hmmm, well Pearl S runs quieter after I wash and wax her.

Just saying.

 

I bet she glows a bit too.

 

Till OP comes back it's speculation, but it's pretty much for sure (ethanol-free) Chevron Supreme Plus.

After we got that ringer tankful up the coast, I even emailed them, asking about ethanol in small town stations. They never responded, of course.

Ah, here we go, visual aid, Canadian Chevron pump:

 

Midgrade is a mix of regular and premium. Blender pumps mix and dispense it at the pump. Stations without those pumps have a midgrade tank in which the delivery truck mixes the regular and premium together.

Midgrade isn't a 50:50 mix. For US 89 midgrade, it is a 2:10 ratio of 93 premium and 87 regular. I have used that ratio to mix midgrade in my car's tank, But I found it a bit cumbersome to bother with regularly.

E10 availability depends on regions and states in the US; more likely in metropolitan areas. Where it is, the "may contain up to 10%" stickers are the most common. There is a station about 40 minutes out of way that has ethanol free regular. It is closer to some lakes, so is likely there for boats. Premium is not guaranteed to be ethanol free; ethanol is used as an octane booster.

Higher octane gas is not harder to ignite with a spark plug. It can withstand higher compression pressures before it spontaneously ignites.

edit: Just occurred to me that HCCI(diesel like gas) engines like Mazda's might have a maximum octane requirement.

 

I've run a tank of Chevron Supreme Plus once or twice, soon after the "miracle" tank from an up-the-coast station, didn't notice much. A little disappointing.

To topic-drift a little, I just dosed the latest tank with the proscribed amount of this:



The back-label says it has petroleum distillate and Polyetheramine (PEA). I was looking for Chevron Techron, but seems like you can't get it up here, or it's expensive on Amazon. Someone speculated it was due to the need to create bilingual labeling, tabernac...

It just seems like the spring mpg improvement is a no-show, so trying one thing at a time, I thought I'd give this a try.

 

Hey Mendel, have you ever tried any of the retailers on this list?
Licensed Brands | Top Tier Gas

 

To the best of my recollection every fillup has been Chevron.