Whay type of Gas?

[Toy4x4]

buster,
see Bob's 1st reply above to answer your question.
I've heard what Bob has said, too, and switched back to 87 quite a while back.

 

[sprintman]

Bob
I'll have to disagree with higher octane being less efficient (that is if I understand what you mean by efficiency). High octane (98 RON) high density fuel is all the rage here in Australia. Started by Shell with Optimax, which an LS1 powered Commodore owning friend put me onto, followed sometime later by BP with Ultimate 98 and later again Mobil with Synergy 8000. The average user sees 15-20% reduction in fuel consumption, 20% for me in an 89 Mazda turbo. Recently I changed to a smaller private company Trafigura Fuels product Evolution 98 which they import from Asian hi-tech refinery (www.trafigura.com.au/evolution) Even better than Optimax. They all smell like rocket fuel! Commodore owner gets 160kms extra per tank, I get extra 100kms in the Mazda (smaller tank). It actually works out cheaper than buying crap std unleaded which is 92 RON. Price differential is 7-9c litre more (say 10%). My Outback 2.5 went from approx 360kms per tank around town to over 500 using Evo 98 and Redline fluids throughout. Shell were the 4th largest in fuel sales in the State of Victoria where Optimax is made, after it was released they went straight to no #1, a position they have held ever since. In a way I think your right in that it's not the high octane so much as it is being a HD fuel. Thats where I think the extra 'energy' or whatever it should be called comes from. I'm surprised these technology fuels are not available in the U.S or Canada, as Mobil is a U.S company.

 

[buster]

I am running regular gas now and it is fine. In fact I'm getting better gas mileage.....

[ December 11, 2002, 09:02 PM: Message edited by: buster ]

 

[TexasTDI]

I have to use 91 octane or higher in my 1998 VW Passat 1.8 Turbo.

 

[buster]

My manual says 87 octane or higher so i'm good with whatever I want to use. I imagine most cars are like this now....

 

[UncleS2]

Sprintman, octane ratings in the USA are an average, (MON + RON)/2. As I understand it, Mechanical Octane Number(MON) refers more to heavily loaded resistance to pinging/pre-ignition. Research Octane Number(RON)tends more to behavior under lighter loads, such as highway cruising. Except for the most heavily loaded situations, if all else is equal, a higher RON should produce better mileage. That sounds like what you're seeing evidence of "Down Under". Wish we could get that gas here!

 

[mojo]

You are correct in describing the diferent engine test procedures for measuring octane numbers, but MON stands for Motor Octane Number. One thing that has not been discussed is the sensitive factor. That is the numercial difference between the RON and MON. The smaller the number, the more closely the R+M/2 (the number that is posted on all gasoline pumps) will correlate with the actual Road Octane number (either the Borderline or Uniontown methods) that is measured in test cars. Unfortunately, the sensitivity quality is never mentioned to the public.

 

[Neonmike22]

quote:

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Originally posted by mkosem:
my engine sparks the cylinders on the exhaust stroke also. do other cars do that?

--Matt

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Most distributorless ignition cars tend to do that. I know my neon does, as well as a friend's eagle talon.

 

[sprintman]

Stuart
They reckon Shell had to spend $500 million upgrading the Geelong refinery in order to produce Optimax. It and Evo 98 are yellowish in colour and it does not smell like gasoline at all. Until the cat 'lights off' or whatever you call it the fumes remind me of a methanol burning sprintcar.

 

[Giles]

quote:

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Originally posted by buster:
My manual says 87 octane or higher so i'm good with whatever I want to use. I imagine most cars are like this now....

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My '02 Explorer is the first car I've owned that warned against running higher octane. On the other hand it will run 85% ethanol fuel so that's something new too. They call it a Flex Fuel Engine where you can mix and match ethanol with gasoline up to 85% or any percentages less than that.