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Question about Octane & Power

7K views 19 replies 9 participants last post by  zebelkhan 
#1 ·
I noticed in the 2009 & 2010 Nissan Murano Owners Manual, it calls for 91 Octane (Premium) Gas. In the 2011-14 Murano Owners Manual, it calls for 87 Octane Gas.

That said, the 2009/10 models were rated at 265hp @ 6000rpm / 248 ft-lbs torque @ 4400rpm. The 2011-14 Muranos are rated at 260hp @ 6000rpm / 240 ft-lbs @ 4400rpm.

That's said, I see that Nissan did this cause they wanted the car to be more affordable to operate, so they lowered the octane/fuel requirements to reduce operating costs for the owner? - hopefully that was the reason.

MY QUESTION IS THIS: If you put Octane 91 in the 2011-14, do you gain that 5hp & 8ft-lbs of torque that was taken away?! :) :hopefully:?!
 
#2 ·
Answer is yes. Murano engine is borderline high compression engine and can benefit from using higher octane premium gas. With premium gas ECU will advance the timing which in turn give you a little more power. However, with gas prices being low these days it may not be as economical as it used to be. Back when gas prices were over $4 a gallon and difference between regular gas (87 Octane) and premium gas (91 Octane) was 20 cents, it made sense to put premium in, enjoy the extra performance and better mileage that went with it, and even though you paid more for a tank of gas, come up about even in total cost per mile. Now, gas prices are lower, and difference in regular and premium prices are often 30 cents or more per gallon. So even though you will get better gas mileage and power, but your overall cost per mile will be higher. Still a small price to pay in my opinion. It also makes sense to use premium gas if you don't drive your Murano that often because premium gas often has additives that keeps the gas in the tank fresh longer.
 
#3 ·
My 2010 had just under 30k miles before I totaled it, and I only ever used 87 octane in it (ok maybe I dropped in premium a couple times a year), never any issues, never any knocking.

Thanks
 
#5 ·
This is great news!, as I care alot about performance, more then fuel economy if I'm completely honest! The gas price in Vancouver, BC Canada where I am from, is around $1 per liter for regular octane 87, but $1.19 for octane 91. So still 20 cents difference. We also have Chevron Octane 94 for I believe is $1.22 or something! Which is pretty good, since we use to be at almost $1.55/L for regular octane 87 not too long ago!

I have another question then.

How do the gases mix? Like say I'm at 1/4 tank on Octane 87, and I fill-up Octane 91 to full tank. Doesn't that mean I don't really have a full tank of Octane 91, but rather 3/4 Octane 91 and 1/4 Octane 87, which is probably Octane 89 or 90 altogether? I think we can get a full real tank of Octane 91 if we do a 2nd full fillup with Octane 91 right? What I think I'll do is run it as low as possible with Octane 87, and fill up a full tank of Octane 94 and see how it goes :). This should net me Octane 91-92 and I'll be rockin'! Does the ECU adjust right away or that fast, or over time?
 
#7 ·
...The gas price in Vancouver, BC Canada where I am from, is around $1 per liter for regular octane 87, but $1.19 for octane 91. So still 20 cents difference....
Considering each gallon is approximately 4 liters, you are looking at almost 80 cents more per gallon, not 20. So your cost per tank will be so high there won't be a payoff.

...How do the gases mix? Like say I'm at 1/4 tank on Octane 87, and I fill-up Octane 91 to full tank. Doesn't that mean I don't really have a full tank of Octane 91, but rather 3/4 Octane 91 and 1/4 Octane 87, which is probably Octane 89 or 90 altogether? I think we can get a full real tank of Octane 91 if we do a 2nd full fillup with Octane 91 right? What I think I'll do is run it as low as possible with Octane 87, and fill up a full tank of Octane 94 and see how it goes :). This should net me Octane 91-92 and I'll be rockin'! Does the ECU adjust right away or that fast, or over time?
ECU measures detonation in the combustion chamber so as Octane rating of the fuel reaching the engine changes it adjusts the timing. But there is a limit on how much that change will be so you may not be "rockin" as much as you think... :)

I would not worry about mixing different octane fuels because it will not do any harm. I would stay away from running the tank too empty to avoid accidentally running the fuel pump dry. You will probably notice the difference over a couple of tank fulls.
 
#8 ·
zebelkhan, thanks for the tip about not running too low-fuel, I never knew that before!

I've decided that I'm only going to use high octane when the weather is nice and I feel like spirited driving (like when I'm going to the states for example from Canada) / long trips etc. But for just daily-city-driving where you hardly go full throttle or race around, I'll just stick to money saving Octane 87!
 
#10 ·
Just crossed my mind, but you know how Gas stations always advertise, the higher octane or 'supreme' gas have more cleaner/additives in it? So like Chevron, says you get more 'techron' in Octane 91 and 'even more techron' in Octane 94. Shell claims the most cleaners in the V-Power 91. So does that mean, those are always use Octane 91 have cleaner engines/fuel systems, because they always running a 'cleaner' in their fuel?
 
#11 ·
This is very similar to the argument about premium (91 Octane) vs regular (87 Octane) use. Most people believe by using higher octane premium gas they get better performance. Not true. Only high compression engines (or near high compression engine such as the ones in the Murano) can put the high octane to use. Using high octane gas in a low compression engine found in most everyday cars is a total waste of money.

Same goes for additives in gas. The major difference between gas sold by different companies is the additive they use in them, and to try to sell more of their expensive gas, they add more detergent to it to make it sound better. However, all gas sold, regardless of the grade must meet certain detergency level standard set by the government. So, are you likely to get more detergent by buying premium gas? Yes, but do you really need that much detergent? Perhaps not. :)
 
#13 ·
Gas companies earn "top tier" status by meeting detergent standards for their gasolines. It's for all grades of gas not just premium. These include most major brands like Mobil Exxon and Sunoco but you can find a full list online.
 
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#14 ·
Zebelkhan, thanks for your explanations on this stuff, its really help to educate us on gasolines!

I also wondering about "Ethanol" what is that stuff? I see sometimes it says something like "Does not contain more then 10% ethanol" or some kind of stamp at gas stations. And some gas stations are dubbed "No Ethanol", like I heard that Shell Vpower, and Chevron 94 is suppose to be ethanol free. So what's this all about, and how does it matter to cars?
 
#15 ·
Don't waste your money. Nobody will notice a 5 hp bump or loss.
 
#17 ·
5 hp & 8 ft-pds of torque are noticeable to many. more importantly, this is just the reduction off from the peak numbers! the decrease in power could be (and likely is) much more over the rest of the torque curve (especially low-end). without a hp/torque curve (or dyno comparison) you can't really know how much power you're losing when running regular, but i believe that it's certainly more than just the 2%/3% peak power loss. I believe that low rpmish wide open throttle power (e.g., hard off-the-line acceleration) suffers noticeably and significantly when using low octane fuel. I have a 96 maxima that will happily eat low octane but it takes away all the oomph from her and I feel the same from the Murano. just my take on it; I don't intend to open up a can of worms here, sorry if I upset anyone.
 
#19 ·
Having had this discussion before, its anecdotal but folks seems to notice that their gas tank seems to go faster when using regular. I would not know since I have always put premium. Funny how you guys are discouraging using premium now that its way cheaper $1.99/gal than several years back when it was close to 5 bucks/gal. I'd say use premium for a few months while its still cheap. Then go back to regular and see for yourself.
 
#20 ·
...Funny how you guys are discouraging using premium now that its way cheaper $1.99/gal than several years back when it was close to 5 bucks/gal. I'd say use premium for a few months while its still cheap. Then go back to regular and see for yourself.
Comparison was for cost per mile between regular and premium for same period. But you are correct, comparing premium gas prices now to before, it is much cheaper now, no question about it.
 
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