Outback XT with Regular fuel?

[Dino]

Hi,

We're thinking about buying an '05 Outback XT but Consumer Reports (and
others) say it requires premium fuel. I was wondering if it's really
required or just if you want "optimum performance"?

thanks!

 

[Fuzzy Logic]

We're thinking about buying an '05 Outback XT but Consumer Reports (and
others) say it requires premium fuel. I was wondering if it's really
required or just if you want "optimum performance"?

If you don't want to use premium fuel consider an Outback Sport or Outback
2.5I as these cars engines require only regular fuel.

You are generally playing a losing (or possibly no win) game when using
regular fuel in an engine designed to run on premium.

Here is a summary from <http://www.baileycar.com/gasoline_html.html>

Cheapskates burning regular in cars designed to run on premium fuel can
expect to trim performance by about the same percent they save at the pump.
If the car is sufficiently new and sophisticated, it may not suffer any ill
effects, but all such skinflints should be ready to switch back to premium
at the first sign of knock or other drivability woes.

and another one from <http://www.straightdope.com/columns/041008.html>

Occasionally you get some genius who takes the opposite tack--he spends an
extra 10 or 20 grand buying a high-performance car, then decides he's going
to save three bucks per tankful using regular instead of premium as
specified. He figures as long as the engine doesn't knock he's OK. Wrong,
carbon monoxide brain. Car engines nowadays contain knock sensors that
detect detonation and automatically retard the spark to compensate. The
delay means maximum gas expansion occurs when the piston is farther along in
its downstroke and thus there's more room in the cylinder head. This reduces
peak cylinder pressure, eliminating knock but also giving you less power and
poorer mileage.

If you really want to try a fuel other than what the manufacturer recommends
here is a method from <http://www.canadiandriver.com/articles/jk/040728.htm>

If you are not sure what fuel to use, start with the fuel grade specified by
the manufacturer and keep track of your fuel economy. Then go up or down a
grade of fuel. If fuel economy stays the same, then stay with the cheapest
grade of the two. If fuel economy drops, return to the original grade of
fuel. Even high performance cars can be driven with regular grade fuel but
only if the driver is aware that the vehicle should be driven sedately.

 

[Dino]

Excellent links! Thanks. I have a Pathfinder and it is also require
premium, but it says I can use regular if I don't need the performance, so I
gather it can detect the change in octane (or rather detect knocking). I
usually burn the mid-grade on long trips but fill up on premium around town
and was just wondering about the XT. I'm going for another test drive today
so I'll see what the manual says about that.

 

[jb]

Excellent links! Thanks. I have a Pathfinder and it is also require

premium, but it says I can use regular if I don't need the performance, so I
gather it can detect the change in octane (or rather detect knocking). I
usually burn the mid-grade on long trips but fill up on premium around town
and was just wondering about the XT. I'm going for another test drive today
so I'll see what the manual says about that.

Wouldn't recommend it.
Basically, a turbocharged car requires premium because of higher intake
temperatures.
If the fuel detonates early, you can easily damage your engine, and it will
not be covered by warranty. And yes, the dealer can pull that info out of
the ECU.

-mark

 

[jabario]

Why do people keep up that BS that lower octane will damage the engine?
You may lose a bit of performance but not enough to notice. If damage
was that easy to do the manufactureres would lose a lot of money on
waaranty repairs. If the manual says premium is "recommended" the
warranty is still in effect regardless of fuel used.
Buy the cheaper gas and dont worry . What if you're travelling in a
hicktown and there's no premium? Ignore the fools who know nothing and
follow every myth they hear about.

 

[Bryan Lee]

The flip side to that. If you do'nt hurt your engine, the lower octane gas
"will" give you lower MPG. You will lose at least 2 or 3 miles per gallon.
I have read on WRX forums as high as 5 mpg lose. Going with the WRX 15
gallon tank you will lose from 20 miles on the low side to 75 miles on the
high side per fill up. You only talking about a $.20 difference a gallon
for premium and regular so you will save $3 a fill up but, you loose 20 to
75 miles a tank. If regular is $ 2.50 per gallon and your car gets about
20mpg. In the best case you end up saving $.50 after buy that extra gallon
of gas to make up for the lost mileage to go the same distance. In the
worst case you spend about $4 more to buy about 3 gallon of gas to make up
for the lost range. So what are you saving? I wonder if the BMW,
Lamborghini, Porsche, Ferrari, and Aston Martin newsgroups and forums get
post a post a week saying " Can I use regular gas in my 911 Turbo or my F430
?" just wondering.

 

[Dino]

I think if it only says recommended than you should be fine as long as you
don't have any knocking. I read the XT manual last night and it said
premium is required and recommended, and to only use regular temporarily if
premium is unavailable, or damage may occur. So for the XT case I'd say you
must use premium. We did some figuring and determined if we drive 16000 or
so miles a year, premium would cost about $225 more than the mid-grade per
year, and that's assuming all hwy driving, or at least $450 more than
regular in the 2.5i, not counting the lesser gas mileage that the turbo has.
It's just something to calculate into the cost of ownership. The turbo sure
is nice though.

 

[marcus153]

Why do people keep up that BS that lower octane will damage the engine?
You may lose a bit of performance but not enough to notice. If damage
was that easy to do the manufactureres would lose a lot of money on
waaranty repairs. If the manual says premium is "recommended" the
warranty is still in effect regardless of fuel used.
Buy the cheaper gas and dont worry . What if you're travelling in a
hicktown and there's no premium? Ignore the fools who know nothing and
follow every myth they hear about.

Here is a link to The Lawrence Livermore National Laboratory website,
with a photo that has been damaged by knocking. I have seen other such
photographs, as well.
http://www-cms.llnl.gov/featured_science_archive/2004/11-04_hydrocarbon.html
or:
http://tinyurl.com/db77s

More info:
http://www.epinions.com/content_2346164356

Thanks!

Marc Sindell
Twin City Subaru Sales
Montpelier, Vermont

 

[Phil]

Speaking from experience, no doubt.

 

[marcus153]

Here is a link to The Lawrence Livermore National Laboratory website,
with a photo that has been damaged by knocking.

Woops. That should say, "...a photo OF A PISTON that has been damaged
by knocking."