Octane grade for Subarus

For a while, anyway, Sunoco had an "ultra" that IIRC was 94.

Reply to
Tim Conway
Loading thread data ...

Throughout Virginia and other places I'vbe driven recently on the east coast, meaning New Jersey and North Carolina, 93 octane is standard. In June we drove to Utah and Arizona, and in many places out west the highest octane was 91 or 92. I thought it had something to do with height above sea level, but I guess not if you don't have

93 in Seattle.
Reply to
John Varela

I have only checked the neaby Chevron and Union 76 stations, so there might be some others out there that do carry 93 or 94 octane gas. I suspect a lot of station owners just don't bother with those higher grades because they don't sell well enough to make it worth. I need to still check some other stations but most of other top tier brands moved out of the state (or at least from the Seattle area) recently, thus the number of brands is pretty limited. There still are some Texaco stations around but I haven't even seen any Shell stations recenly. And I don't even bother with Arco as it carries the lowest quality (hence cheapest) gas anyway.

Reply to
Cameo

87 if it is normally aspirated and 91 if it is turbocharged.
Reply to
JD

Yes, most engines equipped with knock sensors or otherwise adjusted for lower octane will safely run.

*** Not always true. Depending on how the engine is tuned it can only compensate to a point. If it says premium you are taking your chances no matter how old the car is.
Reply to
JD

In the UK they use a different octane measurement. In North America it is (RON+MON)/2; frequently called PON (Pump Octane Number). In the UK they use RON (Research Octane Number) to measure octane; hence the difference. 98 RON is approximately equal to 91 (RON+MON)/2; where MON is the Motor Octane Number.

Reply to
JD

snipped-for-privacy@h7g2000yqn.googlegroups.com...

As someone posted above, the STI can only reliably retard to a point where 'midgrae' can be used safely.

That's why I said 'most'. I'd like to assume that if you own a super- charged or turbo-charged engine equipped high performance vehicle, you know what fuel to use. Some folks even use aircraft fuel or xylene to boost octane ratings for their built-motor beasts.

Reply to
1 Lucky Texan

Indeed, the gas pumps around here indicate the (R+M)/2 octane number. So it gives the average between the Research and Motor octane numbers. Judging from the big difference in octane numbers for the same gas you gave for the UK and US (98 and 91,) then there is twice that difference between the R and M value: 98 and 84. That's quite a difference! I thought it would only be about 8 or 9, not 14.

Reply to
Cameo

It could be. The literature I have says high test US is approx 98-99 RON. It could very be that they are classifying high-test as 93 AKI.

Reply to
JD

Depends on the location. While wrx may "need" 91 in some domiciles putting anything above 89 is a recipe for a lot of backfiring in just about any car due to the questionable quality of 91 and 93. Probably not a problem anywhere in the US though. or do you ever get bad 91 or 93 anywhere in the states (or Canada)?

Reply to
AD

My turbo motor does (2005 WRX)

Reply to
Dave Head

No Sunoco in your area? The ones here all have it.

Reply to
Rune

Nope.

Reply to
Cameo

Last week, Click & Clack explained that, as I expected and mentioned elsethread, lower octane fuel is adequate at high altitude. This explains why 93 octane is common on the east coast but I did not find it available on my recent trip to Colorado, Utah, and Arizona. It does not explain the unavailability of high octane at sea level in Seattle. Is there something in the laws or political climate of Seattle or the state of Washington that is driving away the major oil companies and their high octane fuel?

Reply to
John Varela

Not that I am aware of. Many, if not most of the stations are owned by independent operators who contract with various brands. The same stations often change brands, too. I suppose it's based on where they get the best deals but some major brands just left the state entirely. It could be based on the state's tax structure and other factors unfriendly to the oil companies.

Reply to
Cameo

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.