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Adam Thomas

Shell Gas Only

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2005 RX330 with about 55,000 miles. It only runs well with Shell Premium gas. With any other brand (or grade) the vehicle is a little sluggish.

Has anyone else experienced something like this?

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2005 RX330 with about 55,000 miles. It only runs well with Shell Premium gas. With any other brand (or grade) the vehicle is a little sluggish.

Has anyone else experienced something like this?

Different oil companys spike there gas with different percentages of ethanol. The more ethanol the less power. In addittion, ethanol content can vary, from the same oil company, and from region to region. I've heard that shell, on a whole, generally has less ethanonl. It may well be that shell stations in your area are low on ethanol and, the other brands are high.

In the performace car world, people hunt down stations with low ethanol content. Even 100 octane race fuel can be spiked so much it's no real improvement. I wounldn't be surprised if ther isnt a web site showing low ethanol stations. Don't know though.

Regards, pK

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Different oil companys spike there gas with different percentages of ethanol. The more ethanol the less power. In addittion, ethanol content can vary, from the same oil company, and from region to region. I've heard that shell, on a whole, generally has less ethanonl. It may well be that shell stations in your area are low on ethanol and, the other brands are high.

In the performace car world, people hunt down stations with low ethanol content. Even 100 octane race fuel can be spiked so much it's no real improvement. I wounldn't be surprised if ther isnt a web site showing low ethanol stations. Don't know though.

Regards, pK

So is this particular RX especially sensitive to ethanol levels or is it a problem across the platform? She's asked other RX owners at the gas pump and hasn't run into anyone else with this problem, although that's hardly a scientific poll.

If this RX is sensitive, is there some adjustment than can be made or perhaps a sensor that needs to be replaced? Our problem that there isn't a Shell station on every corner.

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Sensor-yes, adjustment; there arn't really any these days. normally there is a CEL (check engine light) for this sort of problem though. The car is basically requiring a mega vitamin supplement (octane) to offset some systemic deficiency.

Ethanol provides sort of a false octane (power/performance) rating. A properly setup engine will make accomodations for what is really a lower octane gas (ethanole spiked fuel) with out the driver really knowing the difference. This one won't. So yes, there is somthing amiss.

Regards, PK

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What does your book say about what fuel you are supposed to use? My DIL's RX is a '99 (I'm only here because I'm the mechanic for it) and all she has ever used is So.Cal. 87 octane. It has always run fine on it and they have put over a 100k mi on it since they bought it with 32k on it. Her mother bought a new RX in '07 or '08 and it uses premium and she was was complaining about it because of the additional 20 cents a gallon. I am assuming yours does not call for (mandatory) use of Premium. I know that I have read of a spark knock problem being cured in a Ford F-150 PU (a number of them have the problem, I drive one but don't have the problem) by a reflash of the computer. Have no idea if that would help yours or not, but I agree with PK3, it is not normal! By the way, my "04 F-150 has the larger engine (5.4 3V) and has NO spark knock on the 87 octane.

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I don have the book but it’s probably at least 91 but, every car made in the in the last …20-25(?) years has at least a knock sensor system that retards the timing and makes other adjustments to compensate for poor or low octane gas. My wife runs her 99 RX300 and my 91 BMW (wants 94oct) on 87oct with no noticeable difference. I often run my supercharged Porsche on 91oct (wants at least 93) with little noticeable change.

I would have to know more about the symptoms to take a stab at the problem. All I can say is her gas requirements are compensating for some underlying problem. Even if there is no CEL on, you might put an OBCII scanner on it and see if there are any codes. You night also take a visual take a visual look around under the hood and see if there’s something dumb like a cracked hose, a bird nest in the intake duct, whatever.

Regards, PK

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Have used Chevron in all my bikes & cars since 2005, no problem (in this time-frame Shell's personal second choice when Chevron scarce)... As we all know, fuel companies introduce new formula/ types every so often (more or less detergent, oxygenation, MBTE [banned?], ethanol, flex-fuel, etc.), creating great debate about whose best, which really boil's down to personal preference to some degree?

In my limited experience of determining highest fuel quality, bikes (having smaller, most temperamental high compression engines) are best indicator. Basically, if it makes good smooth power there, it's good elsewhere (eliminating detailed analysis - ha ha)... So currently, the seat of the pants results are: Chevron over last 5 years (it's vacillated over past 20 years from Shell, 76, Mobil, Chevron... back & forth roughly in that order). 91 Octane on all...

The common denominator among personal conversations with various fuel haulers over the years is all fuel (regardless of brand) basically comes from same refinery. It's the fuel "formula" which may vary from brand to brand. As an aside, different haulers have also advised to maintain receipts on fuel purchases for the lesser known purpose of determining if (and what) fuel a contributing factor to engine failure (lab tests could determine percentage of engine failure attributed to problem fuel, with potential compensation from supplier). This makes sense to me, especially if using the same gas fairly consistently, and especially if water or incorrect formula proven.

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Hey Code, what do you think about pulling the neg batt terminal for about 5 min to reset the computer in this case? Is it possible the adaptive computer has tweaked timing, etc for 91 octane?

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Hey Code, what do you think about pulling the neg batt terminal for about 5 min to reset the computer in this case? Is it possible the adaptive computer has tweaked timing, etc for 91 octane?

BR- It can't hurt anything, a small chance it could help, but I don't think that is probably going to do it. In the case I mentioned, with the F-150's, Ford had come out with quite a few reflashes over time to fix complaints and problems that weren't necessarily complaints but that Ford had rethought and decided should be reprogrammed. I don't know how often they have to do reflashes currently nor do I know how often other auto co.'s have to do them. Maybe the others have better programmers to begin with. :( I only know that for those that had the problem with detonation (that you clearly shouldn't have with knock sensors and computer controlled timing) were generally told to go to high octane fuel as the answer. That is a totally unacceptable answer when a vehicle states in the owners manual that it is designed to operate on reg. (87 oct.) fuel. There were at least 2 if not more that got the truck reflashed and it cured the problem. It is CLEARLY not normal, and there should be a fix and NO dealer should be telling the owner to go to premium fuel to eliminate the detonation (spark knock) , especially when that cure seldom ever does any more than a partial fix at best. Spark knock is destructive to an engine and the real problem needs to be addressed.

P.S.- I'm not computer knowledgeable but I would think a "reflash" would be different than a "reset" which you would be doing by removing the batt. cable. Try it, it can't hurt.

P.S.S. - Sorry BR and Adam, I went back and re-read the OP and see that it was sluggishness, not spark knock. I would definitely try the batt. disconnect.

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