I regularly put this gas on my car and the rpm at idle is usually somewhere at 700 to 750. But there would be slight hiccups i would feel on idle. I then decided to try out a different gas, and the car, i felt, idled better and the rpm at idle increased a bit say to around 750 to 800. But at the same time i felt it being less responsive on the new gas. Its a feeling and not verified with timing equip, which one is the better gasoline? Both come from well known brands. Ik thinking second one is better and less responsive feel was due to the mix first and second gas in the tank. Opinions?

 

Which are what gas companies and what was the octane?

 

Maybe one gas stations fuel tanks are cleaner than the other station. One station may have water in their tanks.

 

Maybe??

 

I had a similar issue. Cleaned the TB and it went away!!

 

i put gas in various stations of these two brands, to be specific the brand that caused higher rpm is SHell nitro racing fuel with an advertised octane of 97. the other with the lower rpm and less smooth idle is from an affiliate of Saudi Aramco with an advertised octane of 100. these are the two prominent brands where i am. i always put in the 100 octane but was a bit bothered by the less than smooth idle. i tried the shell fuel and got a smoother higher rpm idle but somewhat less responsive performance on spirited driving. i cant point it to water in gas or what not tb as tb this is the response everytime i try shifting to the other gas. now im back to the 100 octane and the lower prm is back. which one do you guys think is better considering these symptoms

 

Here in the States can't get anything above 92 octane unless its race fuel. In California we have only 91 and its full of other crap to further lose of power. California is so stupid....winter blend and summer blend...blah blah....just reasons to jack the price.

 

92 octane gas in the US, Canada, New Zealand and Australia is rated AKI (RON+MON/2). Everywhere else they use RON. So 92 AKI octane gas equates to 97 RON. Same gas just not averaged with the MON rating which is always lower.

 

How I miss Chevron Custom Supreme!

 

I had a similar issue. Cleaned the TB and it went away!!

 

For info, car is a dfi 997.2 if that matters. Dfi engines should only pass air in the tb's

 

Maybe i need a dose of chevron fuel system cleaner.

 

The brand sticker on the gas pump isn't as important as the supplier and infrastructure of the particular gas station. If the station has a dirty tank or water leaking in to the tanks, then no mater if its Bubbas local brew or Chevron Super-Speedway Spiffy, its still gonna run like crap and gunk up the engine and fuel filter.

In Europe, as said, they only use the RON (research octane number), but they tend to have higher ranges of octane than most parts of the US.

Std Normal Unleaded in Germany is 91ROZ, 82.5 MOZ
Super 95 is 95ROZ, 85MOZ
Super+ 98 is 98ROZ, 88 MOZ

Then there is
Shell V-Power at 100Roz/88Moz
Aral or BP Ultimate 102 102Roz 88Moz (95 US Pump Octane Rating)

and great stuff like : (though you need specially fitted fuel systems to use it)
E85 ( 85% ethanol) 104 ROZ
E10 ( 10% ethanol) 95 Roz / 85 Moz

 

Are we saying higher ethanol has higher octane but less power?

 

This may not answer your question but there is some good background information on "Octane" in this link.

http://forums.rennlist.com/rennforum...n-the-usa.html