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Old 12-01-2003, 03:23 PM   #1
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Question Using 87 Octane Gas Good or Bad?

Hi folks, I'm thinking about a 2002 5-sp Boxster for $34k with under 10k miles, but the owner told me he uses 87 regular octane gas. Would that have caused any damage to the engine?

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Old 12-01-2003, 05:36 PM   #2
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Umm, I can't speak for a 02 box, but on the inside of the gas lid on my 03 box S it s

says to put in 93 octane. In the manual, it says you can get away with 90 oct but no lower. I guess the knock sensor auto adjusts for lower octane gas, but I wouldn't recammend using anything but premium gas. The manual says only use 90 in a pinch, and thats 90 not 87, so I would say 87 is mucho bad. However, your talking about a 2.7 liter engine and I have a 3.2, so perhaps my rules don't apply to the 2002 box.
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Old 12-01-2003, 06:23 PM   #3
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I have a 2000 2.7 and the same rules apply, nothing under premium unleaded(93 octane) is acceptable. Even 90 is not a good idea. So 87 would be out of the question. If the guy has been putting 87 in the car he must not care too much about the cars performance.
I might be a little concerned buying a car that has been treated like that. What else has this guy not done properly with it.
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Old 12-01-2003, 07:34 PM   #4
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Completely agree with JfMiller, If the guy puts in 87oct, you dont wont the car trust

us on this one. He obviously is either ignorant of his cars needs, or just doesn't care, which is scary. Most people would spend the extra couple bucks at the pump on a 40k+ car, but apparently he doesn't. Open the gas lid and check it out, it will say 930oct min. It makes you wonder how that cars been treated otherwise, I would assume its had a hard life. I'm suprised the engine doesn't knock or stumble. Did you drive it? Of course he was maybe just giving you a line so the car looks like a more attractive deal. Alot of people baulk at using premium, maybe he thought you were one of those people.
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Old 12-01-2003, 09:28 PM   #5
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thanks guys

that's what i figured, Boxster should be fed with the premium fuel. That's the main concern I'm having over buying an used car, it's impossible to know how the previous owner treats it, I guess it's a risk I have to take. btw, is $34k for about 10,000 miles, 2002 Boxster a good deal? The seller priced it pretty much according to Edmunds/KBB value.
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Old 12-02-2003, 01:48 AM   #6
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FWIW I run 89 pretty frequently, especially for long trips on the highway. I can't honestly say I feel a difference. The engine is supposed to compensate for it, and I don't put it in high gears in low speeds...that's what creates knocking, right?
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Old 12-02-2003, 08:09 AM   #7
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Thumbs down

I've run mid-grade in mine in a pinch (near empty in a station that doesn't sell premium ) and not had a problem.

Like previous posts, what I'd be concerned about is general lack of care by this previous owner. Best case, even if you think they were trying to sell you on the idea that you don't need to run 93 (but they did), they're trying to snow you anyway. Either way sounds like it is questionable.

If you're concerned about the pedigree/care of a used Boxster in general, you might want to check your local PCA chapter's sale listings (or in Excellence magazine). In broad terms, the people that care enough to join an organization focused on the cars are more likely to maintain them properly, IMHO.
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Last edited by donv; 12-02-2003 at 08:12 AM.
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Old 12-02-2003, 09:04 PM   #8
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Octane booster?

Since we are talking about octane levels I thought I might bring this up. There is a 1/8 mile drag strip near my house(I wish there was a real track with curves, but I'm not that lucky). They have a fun run night on friday where you can race as much as you want fro $10. Anyway, when it opens back up next spring, I was going to make a couple passes down the strip with my box S just for fun. If I was to say, add octane booster to the gas, would that give the car an added "kick", or is it a bad idea. Maybe just a waste of money?
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Old 12-03-2003, 03:54 AM   #9
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My understanding of octane is that too little octane causes knocking, and too much octane causes a build up in the engine valves. The car is designed for a particular octane, and a higher octane doesn't do anything for your car. It won't make it go faster nor produce more power.

At least that is my understanding. Perhaps others may have more information, but I've been told that it isn't a good thing to provide too much octane forthe engine.

Good Luck

JBG
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Old 12-30-2003, 05:06 AM   #10
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I read an article some time ago where a senior Porsche engineer pointed out that in many areas of the world premium gas is not available, and the cars accordingly are designed to run on 87 octane, it will not cause a problem. The 93 octane requirement is there only to guarantee that the Porsche will perform as advertised. Personally, I use premium.
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Old 12-30-2003, 10:42 AM   #11
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computer automatically adjusts

According to the owner's manual, the computer automatically (knock sensor) adjusts the timing and ignition to accomodate lower octane level gas. Seems likely this would reduce performance but not hurt the motor.
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Old 12-30-2003, 01:31 PM   #12
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My manual says 90 in the min. So I know it will adjust for 90oct. However it may not be able to make a dramatic adjustment required for the 87oct.
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Old 01-07-2004, 12:49 PM   #13
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WARNING! You don't have to hear the knock for the car to be knocking!
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Old 01-11-2004, 08:14 AM   #14
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I agree with FXSTB, you dont have to be able to hear the knocking for it to be actually doing it. I realize the car manufacturer probably does make the car to run on any fuels that might be available in the area the car was sold in, but why would anyone want to put anything less then the best they can get at the station for their Porsche. If its a question of affording the gas, then maybe a honda would be better for some folk :/ Noone should ever short change on the extras for their high end car and if price is a factor I would suggest looking at other lines of vehicles that wont break your bank account.
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