Is Premium Fuel really needed?

Submitted by Canada Quest SL on Mon, 2008-01-14 01:23. 2004+ Nissan Quest

Is there a difference between 87 Octane and 91 Octane for the '07 Quest? The 2007 manual suggests 91; The 2004 - 2006 manuals suggest 87. Isn't the engine still the same? Is 91 octane "needed" or "suggested"? I've only been using regular. Will emissions be effected? What's the mileage difference? Is it worth the extra $$$ ? Please give me your opinion.

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I am in the process of

Submitted by Virion on Thu, 2008-04-03 22:06.

I am in the process of testing this. I tested this theory with my previous 2k2 Maxima and using premium increased hp by 8hp. (dyno tested) Fuel economy decreased by approximately 8-10% which more than paid to the additional cost of premium. So far using premium has increased fuel economy by 1-2mpg average. I don't have enough data using premium on our quest to give a good long term average. This of course is non scientific as it's not in a controlled environment, but I am driving the same routes and use the same driving habits daily. I will post my results within the next few months.

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Actually...

Submitted by twosteppin jimi on Tue, 2008-03-25 16:35.

Your engine will not knock because the ecu retards the timing preventing it from happening thus degrading the power and possibly the mileage. FWIW, I've been privileged to own may fine Nissan autos and many were engineered to run on premium. Early on, I too was skeptic and ran low grade with no real "visual" effects in terms of power or mileage. But if you plan of keeping you car for 120k+ miles, you'll see the effects. All the sensors it takes to make the engine run smooth will expire early such as O2 and Knock sensors. These sensors effectively work overtime to make the engine run adequately. Do the math: Premium is only $.20 more (or you're paying too much) than low-grade. It's safe to assume that on average, we'll get 20 mpg in our Quests. Over the course 120k miles, you will have spent $1200 extra for premium fuel. To put that into perspective. I was quoted $900 to replace the knock sensor on my Infiniti I30t just 2 years ago and $500 to replace the O2 sensors earlier. The biggest dis-justice you can do is put in mid-grade... it doesn't provide a high enough ratio of anti-knock hydrocarbons to prevent the ecu from retarding the timing and you've paid $.10 more a gallon for it!

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better mileage with mid-grade

Submitted by wakramer on Fri, 2008-01-18 12:53.

I can't speak for performance but our '05 definitely gets better mileage with mid-grade or premium. If we use 87 octane the mileage is consistently around the mid 19's. With mid-grade or premium we get close to 21 mpg. 87 octane works fine and will not ping since the ecu retards ignition timing to prevent pinging. Retarded timing reduces power but I'm not sure by how much.

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not really...

Submitted by Beef Supreme on Tue, 2008-01-15 10:43.

If you don't experience engine pinging or knocking, than it is acceptable to use 87. For more info, take a look at this link at CarTalk.

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Not beneficial

Submitted by Virion on Sun, 2008-04-20 10:30.

The car talk link you provided has no relevance on this subject whatsoever. Their topic addresses, will cars that are spec'd to run on regular benefit from premium fuel. We all know the answer to that is clearly no. As others have mentioned when you use regular fuel your knock sensors and 02 sensors will be working overtime to keep the engine from knocking. It retards the engine timing and decreases hp/tq. This is something I personally have proof of from dyno testing. Not on the Quest, but on my past 2k2 Maxima which had the same VQ35. In my testing I am still averaging 1.5-2mpg higher using premium fuel. Unfortunately, the heat is approaching and air conditioning will used frequently since we have an infant. Even if you didn't receive a boost in fuel economy, if your tank was bone dry and you filled up with 20 gallons of premium, it's only $4 a tank more. Don't go to Starbucks one day or don't eat fast food one day a week. The cost of replacing the knock sensor and/or 02 sensor will more than pay for the premium. Nissan's knock sensors while good will definitely fail over time.

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Failing sensors with lower octane?

Submitted by GLVQuest on Thu, 2008-04-24 13:54.

I understand that lower octane=lower performance, but why would these sensors have to "work overtime" to prevent the engine from knocking? I thought that they are always sensing and controlling the timing no matter what octane is being used and in fact are constantly adjusting to even minor fluctuations in octane (along with other conditions). Is that not correct?

Thanks -
Greg
Potential buyer of 04 Quest 3.5SE

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Not buying a Quest

Submitted by GLVQuest on Fri, 2008-04-25 15:15.

I am still interested in the answer to the octane question, but we are actually buying an '02 Mazda MPV, much better for our current budget as we are getting a good deal. Also the 2nd row windows roll down which is very nice for the kids. May trade up to an '07 or newer Quest later on since they moved the gauges back in front of the driver (plus will need more room for bigger kids later on).

Thanks and everyone enjoy driving your 04+ Quests, we got to keep it a couple days to try it out and it is an amazing machine.

Greg

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The Nissan Quest Owner's

Submitted by mnemonicj on Thu, 2008-01-31 19:41.

The Nissan Quest Owner's Manual recommends premium gas, so I would use premium gas even if you don't hear a knocking. Using regular gas can cause lower performance and lower fuel economy and often times you won't realize the performance hit that you take using regular gas until you really need it, like when passing an 18 wheeler on a 2-lane highway or gunning it up an on-ramp to speed up to traffic.

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Premium fuel

Submitted by TNSteve on Tue, 2008-03-25 10:33.

I find that regular 87 fuel works just as well. I found no MPG increase nor significant "power" increase using 93 fuel. No knocks, no pings. I do, however, use only Shell, Mobil/Exxon, or BP gasoline. This observation is based on around town driving, as well as several lengthy highway trips across the Southeastern US.

2007 SE

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The Usual Suspects...

Submitted by rgwondering on Sun, 2008-04-20 08:12.

As a kid I worked in a gas station. (hold onto your hats) I was shocked to discover that the owner of the station had a deal going with the driver of the tanker that delivered our fuel. It was an Amoco station (now BP). The deal was for 100 bucks on the side the driver would dump 'regular' gas into the 'premium' tank. And from what I understood, this practice went on everywhere. As a result of my 'insider' knowledge I never buy premium gas. Period. I'd recommend your money be better spent adding aftermarket octane booster additives. At least you'll know your not getting robbed at the pump.

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