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Discussion Starter #1
i just want to know which Brand and year of gasoline did you use, and which is better??


i am using Amoco, 93...


thanks
 

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I use 7 eleven super premium but I am thinking about changing to mid grade becuase the service guy told me it wouldnt make much of a difference and it would save some money. Any thoughts?
 

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i use mstly sheel or chevron, several fillups shell and one chevron. repeat. (m)

For the shell i use 89 grade fule (mid)
and for the chevron i use the high grade.

Shell's gas has special additive to make the car feel stronger, somehow. Chevron gas has cleaner/detergent to clean the inside.
So several high-combustions cycle and one cleaning cycle, intuitively.
 

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My point of view is all gasoline is the same except for their detergent additive packages. I usually use whichever name brand gas station is nearby, 93 octane. When I used to live in the SF Bay Area, I would buy Chevron exclusively because I thought Techron was better than all the other additives.
 

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Discussion Starter #5
what is the # means when i go to the gas station,, 87, 89, 91, 93??

is that the year or octane #??


thanks
 

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william said:
what is the # means when i go to the gas station,, 87, 89, 91, 93??

is that the year or octane #??


thanks

Octane. I would not want to buy 1987 gas, or 1993 for that matter!

The Murano can use 87 (regular) octane or for improved performance, Nissan recommends 91 or higher octane. However, using 87 will not damage the engine as the computer can control timing for whichever octane you use.
 

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Yes, the comp will retard performance if the octane is too low... but I can't suggest running it like that forever. I'd go with at least mid-grade and give the engine a rest, let it concentrate on great performance :)

I usually fill up with Amoco 93. The station is pretty busy too, so I don't have the fear of the tanks getting water in them from lack of use/re-filling.

The lowest I've put in it was 92 or 91, I can't remember. It was Getty gas.
 

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I ran 87 for a while and noticed a drop off in performance so I swithced to 89.
 

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I use 93 octane. I tried the 87 (regular) and 89 (mid-grade) but did not like the performance loss (it was very noticible with the 87).

Brands? Mostly Shell, Citgo, BP (Amoco), Mobil. All have pretty good detergent quality. I've been using those brands in all my cars (mostly high performance sports cars) over the past 30 years with no problems. I stay away from cheapo, no-name, or local-yokel gas stations since I don't know what brand of gasoline they use or how old that gas might be in their tanks.

I, too, try to go to gas stations in busier areas since those tend to keep a steady flow of newer gas in their storage tanks (less water build-up).

I have been told to not fill at a station that is currently having its storage tanks filled (i.e., by a tanker). They say that the filling process stirs up sediment in the underground storage tanks which may find its way through the filling pumps to your gas tank. I am not sure if that is true, or if there is a filter system in each filling pump that would prevent this, but I stay away from stations that are refillling their tanks just to be sure.
 

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I buy the cheapest 87 octane I can find at any place that looks safe enough to buy gas at. If it will light with a match and doesn't knock its good enough for me. I'd love to see dyno tests with different octanes. I suspect the benefit of higher octane is much the same as a good wax and detail job, they both make you feel like the thing runs better. Just my relatively uninformed but experience based opinion.YMMV.

George

P.S.: my 96 Maxima knocked with 87 octane. Drove me nuts so I used 89. Same with my 84 King Cab 4x4 with its Weber carb and aftermarket headers.
 

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A lesson in Octane

Octane itself does NOT make horsepower. Only the engine can make horsepower. Horsepower depends on a number of factors including engine size, the number of cylinders, positive air flow induction (supercharging, turbocharging), etc. However, no matter what the engine, the most effective and efficient means of optimizing horsepower is to allow the pistons to compress the fuel/air mixture in the cylinders as much as possible before lighting the spark, while avoiding pre-ignition.

Today's engines accomplish this by modifying the spark curve (i.e., when the spark plugs fire) so that the fuel/gas mixture ignites at the proper moment when the piston is at its optimal position in the cylinder, short of detonation (also known as knock or pre-ignition). The closer you can get to that point, the more power the engine can extract from the mixture.

Why? Because compressing the mix causes a more energetic burn which equals more power. By the way, the fuel/air mix actually burns across the cylinder, albeit very quickly. It should not explode.

Too much compression (before the spark) and the mix fires on its own causing detonation (it literally explodes). Unless you are a diesel engine, this is very, very bad and damage will occur quickly (detonation blows holes in pistons, bends crankshafts, and has been known to blow cylinder heads clean off high compression engines). Too little compression (that is, igniting too early) and the mix burns off too quickly, too early (it actually works against the piston's upstroke), and engine's power suffers.

Higher octane suppresses that preignition point (i.e., allows greater compression), so that the piston can compress the fuel/air mix closer to the ideal spark point for that engine. Lower octane gas does not compress as well and can pre-ignite at high compression. In higher compression (or super-/turbo charged) engines, this causes knock. In lower performance engines where compression ratios are lower, octane means little so they can get away with lower octane.

However, in today's computer-controlled engines, a knock sensor senses preiginition and tells the car's computer to 'retard' the spark timing (i.e., fire the spark sooner). This prevents knocking but also robs the engine of a degree of power. At higher octanes levels, knock is suppressed and the computer 'advances' the spark timing (spark later) so that the engine can reach its full HP potential. This is why even higher compression engines these days can use lower grade gas. They may not make their full horsepower, but they will run.

Realize this: higher octane will NOT allow a rated 200 HP engine to make 250 HP, but lower octane may only allow it to make 180 HP. Lower performance engines will likely see very little difference in higher octane usage since they don't have much power potential to start with. But higher performance engines with higher HP potential (like in the MO) will definitely benefit. If you have a 2 ton vehicle powered by a scrawny 150HP engine, all the octane in the world ain't gonna make perform like a MO.

So, if your engine is rated to produce 245 HP, like the MO, for example, higher octane will help it to reach that goal. Lower octane will cause the timing to retard and keep the engine from realizing its full glory.

Will you damage your engine by using lower octane? Probably not, because of the knock sensor. Will you notice a difference? Yes you will....unless you choose not to. The engine will run, the car will move, and life is good, if that's all you're looking for. If you don't plan on feeling the floorboard up against the back of the accelerator, if that idiot next to you in his Grand Cherokee smiling and revving his engine doesn't represent a challenge, or if the MO is simply a cool looking mini-van to you, then by all means, go for the 87 octane.

But if you want to maximize this vehicle's performance (and the MO is a performance vehicle in my book...maybe not by sports car standards, but definitely by SUV standards), you need the higher octane. I think many readers of this forum, including myself, fall into the performance-minded category which was a big part of the MO's attraction.

By the way, if you live in very hilly or mountainous areas, you will notice the difference in uphill climbing by using the higher octane fuel. Uphill driving also induces knock because of the added demand on the engine. It is probably better for your engine to use a higher octane in this case.

I have noticed a true difference in using varying octanes. Having driven sport cars hard all my life (the MO is my first break from that bad habit), I can tell performance differences as slight as lower pressure in one tire. I have timed acceleration gains from using higher octane in my other cars and they are very real. I have not done that on this vehicle, but I feel confident in my 'gut' and in my experience in trying different grades of gas in it, that octane does make a difference.

The moral is, you get out (of your engine) what you put in and you will feel what you choose to feel or not feel (performance-wise).

Care to race your 87 octane against my 92?
 

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My take is use both grades - regular and premium, and if you cannot feel the difference (a lot of people can't since they don't gun it at every green light) then use regular. The cost difference between regular and premium is usually high enough so that you will not recover the cost in fuel economy going with super (where I live, regular is about 15% cheaper than super, and the difference in fuel economy from what I have measured is far less than 15%). That said, I still use super, since I have a lead foot! :D
 

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Stonemaster, thanks for your excellent review of how octane effects engine performance. I think the science is there but I'm still a little skeptical on the practical effects. What you are absolutely right about is this:

"The moral is, you get out (of your engine) what you put in and you will feel what you choose to feel or not feel (performance-wise). "

Bingo. From aftermarket air cleaners to platinum three pronged spark plugs to little turbo fans you stick in the intake inlets there are a world of products that convince us that we get more performance and if we believe it we feel it. In that regard, there is no harm other than to your wallet. But if you think you can feel those platinum plugs in the seat of your pants, hey, more power to ya.

But let's put all this touchy feely stuff aside. You might be Dale Earnhardt or Bobby Rahal, but I doubt it. So for serious practical purposes it really isn't fair for you to ask us to trust your sports car experience when it comes to sensing a difference of 2 octane or a slight difference of air pressure in one tire. You very well might be able to but we don't really know that.

So what I want to see is numbers. Dyno numbers from a reliable source. I've seen them for spark plugs (zero difference), I've seen them for the little turbo whirly gigs (zero difference) and I've seen them for K&N airfilters (minimal improvement). (And to be clear, better plugs and filters can obviously have benefits other than increased performance so lets don't start that thread again). I've even seen dyno tests on that octane booster crap you add to your gas...nothing. So can anyone show us some dyno numbers? At different altitudes, etc?

And I'm hoping someone can. I'd love to be proved stone cold wrong. A few pennies at the pump to boost performance would be great. But let's say we do get the numbers. How much actual horsepower difference will it really be, and where on the HP/RPM curve will it be? Any guesses or predictions? Let's say, in our wildest optimistic dreams that one gains 10 additional HP at the _flywheel_ at 3000 rpm. How much will that translate to at the wheels? In our wildest most optimistic dreams maybe 5 or 6 HP? So lets take our 5 HP and plug it in to our Murano. How many of us mortals, who can't tell when one tire is slightly low, are going to notice that 5 HP? How about the more realistic estimate of 1 HP at the wheels?

But again, for anyone whose "gut" tells them that the higher octane gives them better performance, what is a difference of a mere $4 per tank of gas? If you own a $30,000+ Murano, $4 just aint that much. Go for it. Besides, the Murano manual does say for best performance use 93 octane. Of course that is the same manual that tells you not to carry a drink in the cupholder while you are driving because it could spill...causing serious injury or death.

George
 

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There a many factors that ultimately determine how much performance you can extract from an engine. But I don't think any tests or performance numbers would be good enough for a skeptic because there will always be some factor or factors that will discount whatever data is brought to the table. Sure, wonder spark plugs, high flow air filters, and cheapo turbo fans are nothing more than marketing ploys, but some add-ons like true turbo- or superchargers, nitrous, better intake/exhaust system do work. Some of those gizmos might even work if your engine is in such bad shape that ANYTHING (especially new spark plugs of any variety) would make a real difference.

Anyone can put a car on a dyno, play with a number of engine adjustments, and prove their new gizmo or "snake-oil, motion potion" adds horsepower. A warm day vs a cold one will also affect performance as will the general state of the engine's health (broken-in, not broken-in, clean plugs, etc.).

I like Eric L.'s assessment. Fill-up using one and then the other and you make your own assessment. Performance is highly subjective, unless you're talking some major increase (say 200 vs. 300 HP, over 200 vs 205 HP).

My opinion was just that...my opinion... based on my experience with this and many other vehicles, take it or leave it...as is everyone else's assessment in this thread.
 

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It is true that no one really knows for the Murano's engine, what the horsepower difference would be between 87 regular and 91+ premium. On Maxima.org I remember a few years back that dyno runs showed a very slight decrease in overall power running regular (and that engine at 3.0L is pretty much the same as the Murano's engine). With the sophisticated engine electronics nowadays, I doubt you will ever hear knock on 87 octane in the Murano. However, a caveat to that is that there is a trend of knock sensor failures with the Maxima (95-99) at around the 75,000 mile mark. It does not trip the CEL and is a pain to replace. I believe however, that knock sensor failure was completely unrelated to the type of fuel used.

Here are some facts however:

1) Owners manual recommends 91 octane or higher for maximum performance

2) Use of 87 regular is acceptable, and will not harm the engine (despite what some people will say that using the cheap stuff will cause cylinder meltdown due to pinging)

3) If your knock sensor and ECU are functioning correctly, you should not get any knock from 87 octane. Lack of pinging, however, does not mean the engine is performing at its highest efficiency.

4) The mileage difference between super and regular is generally not significant when compared to the difference in price between gasoline grades. The choice to use super is mainly one of personal preference to get "maximum performance" from the engine
 

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Eric L. said:
However, a caveat to that is that there is a trend of knock sensor failures with the Maxima (95-99) at around the 75,000 mile mark. It does not trip the CEL and is a pain to replace. I believe however, that knock sensor failure was completely unrelated to the type of fuel used.
My 1995 Maxima was put to death (totaled) at 190,xxx miles. The engine had never seen anything other than Premium and the knock sensor was original.

My 00 Maxima (same 3.0 liter engine) currently has 138,xxx miles on it, gets the same diet of 93 octane premium and is still on it's original knock sensor.

I suspect that the more a part gets used (running 87 all the time for example) the more it may tend to fail.

That said I'm running a mix of 89 or 93 in the Murano and I can't tell any difference in performance or noticeable difference in MPG.

Here's my 03 Murano's mileage history, sorted in descending MPG.

There is no (in my mind) discerable pattern other than 89 gives descent mileage and 93 doesn't significantly improve it.

Date ODO Gas $ Gal. Miles MPG Grade
7/28/2003 379 $19.46 11.803 288 24.4 89
9/10/2003 4,592 $34.52 19.189 411 21.4 89
10/11/2003 6,502 $33.25 19.121 409 21.4 89
8/12/2003 2,495 $33.41 18.572 380 20.5 93
11/2/2003 7,839 $32.65 19.683 402 20.4 89
8/23/2003 3,195 $35.12 18.993 386 20.3 89
9/20/2003 5,325 $34.20 18.908 384 20.3 93
9/27/2003 5,699 $31.75 18.690 374 20.0 93
11/28/2003 8,817 $33.12 19.157 377 19.7 93
10/18/2003 7,121 $35.17 20.702 403 19.5 89
10/17/2003 6,718 $19.27 11.146 216 19.4 89
9/17/2003 4,941 $31.60 18.066 350 19.4 89
10/24/2003 7,477 $31.11 18.753 356 19.0 89
10/4/2003 6,094 $34.73 20.937 395 18.9 89
8/17/2003 2,809 $32.56 18.726 353 18.9 89
12/15/2003 9,940 $21.63 12.808 241 18.8 93
12/18/2003 10,070 $28.85 17.604 327 18.6 89
12/14/2003 9,485 $34.05 19.810 367 18.5 93
8/3/2003 1,438 $16.75 10.217 189 18.5 93
8/28/2003 3,895 $31.30 16.062 295 18.4 93
9/1/2003 4,181 $38.53 20.613 375 18.2 89
11/22/2003 8,626 $23.40 13.304 242 18.2 93
11/13/2003 8,215 $33.04 19.798 360 18.2 93
8/27/2003 3,445 $35.18 17.597 317 18.0 93
8/1/2003 1,250 $30.95 19.000 335 17.6 93
12/5/2003 9,118 $29.28 17.440 302 17.3 93
12/26/2003 10,374 $31.82 19.898 339 17.0 89
8/4/2003 1,775 $34.13 19.970 337 16.9 93
7/31/2003 915 $31.00 19.146 313 16.3 93
8/6/2003 2,088 $36.31 20.183 312 15.5 93
7/30/2003 602 $30.54 17.262 223 12.9 93

TOTAL $958.68 553.16 10,358 18.7
 

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Just to clear things up, the 2003 Murano manual says:

"Use unleaded regular gasoline with an octane rating of at least 87 AKI (Anti-Knock Index) number (Research octane number 91).

For improved vehicle performance NISSAN recommends the use of unleaded premium gasoline with an octane rating of at least 91 AKI number (Research octane number 96)."

Talk about a bunch of double-speak, as if NISSAN recommends 91 and someone else says you can use 87.

My 96 Maxima knocked with 87 octane after about 70K miles ( I guess the knock sensor failed...so what). After that, a tank of regular caused the CEL to come on. A tank of 93 would cause it to go off. I frequently ran 2 tanks of regular to one tank of premium. I never paid attention to the CEL, ever, and at 170K the engine purred like a kitten and broke 120 mph with ease.

George
 

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Snopes said:
Just to clear things up, the 2003 Murano manual says:

"Use unleaded regular gasoline with an octane rating of at least 87 AKI (Anti-Knock Index) number (Research octane number 91).

For improved vehicle performance NISSAN recommends the use of unleaded premium gasoline with an octane rating of at least 91 AKI number (Research octane number 96)."

Talk about a bunch of double-speak, as if NISSAN recommends 91 and someone else says you can use 87.

My 96 Maxima knocked with 87 octane after about 70K miles ( I guess the knock sensor failed...so what). After that, a tank of regular caused the CEL to come on. A tank of 93 would cause it to go off. I frequently ran 2 tanks of regular to one tank of premium. I never paid attention to the CEL, ever, and at 170K the engine purred like a kitten and broke 120 mph with ease.

George
The knock sensor will not trip a check engine light. You probably had some other sensor go bad, like an O2 sensor. That is very common. The ECU has a mapped default in case any sensor goes bad, sort of a "failsafe" mode.
 

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Either way, the CEL went off with every tank of premium and came back on with every tank of regular. The CEL takes on the charma of the boy who cried wolf and is possibly the worst idiot light of the bunch. I think it was designed as a cash flow maintanence light for dealerships. In any case, ignoring it for 7 years did not seem to have an appreciable impact on my Maxima. Now the impact that totalled it is another story, but suffice it to say that my wife and daughter were uninjured while the passenger of the at fault late model Accord spent 3 weeks in the hospital (but recovered completely, PTL).

George
 
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