Outback XT with Regular fuel?

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!

Reply to
Dino
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"Dino" wrote in news:nKydnQfuSrLGDnvfRVn- snipped-for-privacy@comcast.com:

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

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

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

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.

Reply to
Fuzzy Logic

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. :-)

Reply to
Dino

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

Reply to
jb

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.

Reply to
jabario

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
Reply to
Bryan Lee

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. :-)

Reply to
Dino

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.

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Thanks!

Marc Sindell Twin City Subaru Sales Montpelier, Vermont

Reply to
marcus153

Speaking from experience, no doubt.

Reply to
Phil

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

Reply to
marcus153

replying to Dino, Kurt Brinson wrote: We bought used 2005 XT OUTBACK and it drives great and fast! I decided use Premium only; as not worth loosing Engine or Turbo and will have car for 6 to 10 years!

Reply to
Kurt Brinson

Premium fuel doesn't do a thing for engine longevity. Regular oil changes does.

Yousuf Khan

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Reply to
Yousuf Khan

If the owner's manual doesn't call for premium (either requiring or recommending it), you're wasting your money. All premium gas does is increase pre-ignition (knock) resistance.

Back in the day, some brands of premium had better additives and detergents than their regular or mid grades. If you buy what is designated as Top Tier gas, all grades have the same additives. Not sure if non-Top Tier brands these days also have identical additives in all grades.

Reply to
Wade Garrett

Two points for your consideration.

  1. Modern engines often have computers adjusting/compensating for ignition variances. It might not be the best policy for performance and fuel economy, but it is possible to run an engine which has premium fuel "recommended", on regular fuel.

  1. Top-tier fuels may well have the same additives for each grade of gasoline, but there will be increasing amounts, or different ratios of those additives in the higher octane rated fuels. Without being a fuel specialist, it is difficult to know whether these differences really affect overall performance, fuel economy or engine life.

Reply to
Darryl Johnson

Clever argument technique!

Postulate a difference that doesn't exist, next- claim that non-existent difference may have performance effects, and then finally conclude that only an expert can evaluate those non-existent differences for sure!

No doubt the gullible will be taken in...

Plaintiff and defense lawyers use this approach all the time!!

Reply to
Wade Garrett

What a weird response! Oh well: takes all kinds.

Reply to
Darryl Johnson

Reply to
clare

No, they do not all have the same additives in all grades. The package in top tier gas will be closer than in a lot of others.

Reply to
clare

Wade, are you an automotive engineer? Or even a qualified auto mechanic?? I doubt it.

The 2005 XT is a 2.5 liter turbo engine and according to Subaru it "requires" premium fuel. The engine management system can detune the engine to compensate somewhat for lower octane fuel if you drive conservatively, but if you are heavy on the throttle you WILL damage the engine on regular fuel. You will also use significantly more fuel; to the point you are just as far ahead to use premium fuel and back out of the throttle so the engine is only producing as much power as the detuned engine produces on regular. The 3.0 H6 was also a "premium only" engine. The new 3.6 can safely run on regular - as can all the current non-turbo engines. Not sure about the current crop of turbo 4's - but if the manual says "premium required" don't second guess the engineers. You don't know enough to advise others to disregard the manufacturers requirements.

Reply to
clare

That's what they say.

Reply to
clare

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