hpowders

You seem to be very intelligent.

Leader

It's marketing that makes us think gas brands are different. Since they're all coming out of the exact same refineries (of which there are fewer and fewer), buy your gas where they sell a lot of it. That way you know you're getting relatively "fresh" stuff.
If you want to pay more for Shell, Chevron, or whatever...big oil loves you.

Ynot

My Porsche and Mercedes only gets Shell and Conoco, 91 octane, b/c of the high altitude, we don't need or have 93 octane. The Conoco near my house is only a few pennies from the cheapest. I guess I'm a sucker for their marking ploy. I feel weird putting cheap gas in an expensive car. We don't have BP, Exxon, Chevron here (or least not anywhere near). My minivan and suv gets safeway or the cheapest gas.

Skibum

Classic examples here of marketing ploys that work.

Charlie C

When in MA, I use Shell 93 or Mobil if there's not Shell around.

In CA, I use Shell 91 (highest available).

I can't understand why they limit octane to 91 in CA. Maybe it's supposed to be cleaner (less pollution) but on a CA to MA trip, I found my miles per gallon increased noticeably when the available gas octane was 93. So you have to use more gas with 91 octane so I wonder if it wouldn't be cleaner to run higher octane and use less gas. Just my 2 cents or 2 octanes.

No HTwo O

The high altitude robs your power. The 91 octane vs the 93 is another power drop. So, I'm not following your logic or agree with your statement.

Take a look at this recent post, and pay special attention to Jean's comments:

https://rennlist.com/forums/993-turb...uals-ok-2.html

Domer911

In Denver, for example, "regular unleaded" has a minimum octane rating of 85. Closer to sea level, the same stuff has a minimum octane rating of 87. Not sure if its a function of altitude, though, because I am told than in MN regular is also 85. this may have some relevance to this discussion, or it may be more useless trivia from me.

roadrat

Shell or Exxon 93.

I've avoided Chevron since the 80's when it used to cause problems in my Reliant K car. What a sweet ride that was

Ynot

Okay, so we don't have 91 octane is what I should have said. I found the explanation from Wiki

"United States: in the US octane rating is displayed in AKI. In the Rocky Mountain (high elevation) states, 85 AKI (90 RON) is the minimum octane, and 91 AKI (95 RON) is the maximum octane available in fuel[citation needed]. The reason for this is that in higher-elevation areas, a typical naturally-aspirated engine draws in less air mass per cycle because of the reduced density of the atmosphere. This directly translates to less fuel and reduced absolute compression in the cylinder, therefore deterring knock. It is safe to fill a carbureted car that normally takes 87 AKI fuel at sea level with 85 AKI fuel in the mountains, but at sea level the fuel may cause damage to the engine."

No HTwo O

Don't you mean to say you don't have access to 93 octane? Not 91.

cab&coupe

Ditto... although Shell has pulled out of the Inland Northwest (WA, ID) a few months ago.

helispud

We still have Shell in Southern Idaho, but it's now usually polluted with ethanol. On the positive side it's 93 octane. Recently the local Chevron's have gone to 93 octane NON-ethanol. Quite interesting as we are over 4000 feet altitude and until a few months ago only 91 octane was available.

swajames

The US uses a different measurement scale...

93 here is directly equivalent to 99 in the UK. It is essentially the same octane rating, measured on two different scales - the UK uses RON, the US uses AKI.

Alan C.

I prefer whatever my wife pays for to fill the tank.

cab&coupe

Good to know. More specifically... eastern WA and northern ID (Spokane/Coeur d'Alene) area