Octane grade for Subarus

[Tim Conway]

Where do you find 93 octane gas? Here in the Puget Sound area the highest
octane gas I find is 92.

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

 

[John Varela]

Where do you find 93 octane gas? Here in the Puget Sound area the
highest octane gas I find is 92.

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.

 

[Cameo]

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.

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.

 

[JD]

I wonder what octane ratings are specified in the Owner's Manual of the
latest Legacy and Impreza models (2010 & 2011.)

87 if it is normally aspirated and 91 if it is turbocharged.

 

[JD]

The majority of cars that "require" premium fuel do just fine without
it. Are people so gullible to think their car won't run on regular
fuel? What if there was none available in the sticks? Use regular and
save a lot a money!

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.

 

[JD]

"Cameo" wrote in message
The difference between US and UK fuels' octane rating is interesting.
Our standard supermarket low octane petrol is rated at 95 octane.
We also have 99 octane fuel (+5% bio fuel) easily available which I run my
WRX
on and yes, it does make a difference. Most noticeable is much smoother
running and acceleration from low revs. An overall better performance,
lower consumption and no residue build-up is claimed. On one of the rare
occasions I monitored fuel consumption on a long run I averaged 34 mpg
which surprised the hell out of me!!

-C-
Anything is possible if you don't
know what you're talking about

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.

 

[1 Lucky Texan]

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.

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.

 

[Cameo]

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.

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.

 

[JD]

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.

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.

 

[AD]

Do Subarus need premium gas to run?

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)?

 

[Dave Head]

Do Subarus need premium gas to run?

My turbo motor does (2005 WRX)

 

[Rune]

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

 

[Cameo]

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

Nope.

 

[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.

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?

 

[Cameo]

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?

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.