Is 91 octane a must for my car?

[Kestas]

I have a 2010 Murano with 80K - new to me. I see the filler door gives a recommendation of using 91 octane gasoline. The wording makes it sound optional, which suggests the engine has a knock sensor. If I can get away with it, I don't see the point in using premium, when it costs 23% more than regular ($2.65 vs $2.13). I don't believe I'd lose 23% gas mileage, or harm the engine. It may have made sense back when when it only cost 11% more ($3.90 vs $3.50) or less. What do you think?

 

[PRND3L]

Per the owners manual:

"FUEL RECOMMENDATION:
NISSAN recommends the use of unleaded
premium gasoline with an octane rating of at
least 91 AKI (Anti-Knock Index) number (Research
octane number 98).
If unleaded premium gasoline is not available,
you may use unleaded regular gasoline with an
octane rating of at least 87 AKI number
(Research octane number 91), but you may
notice a decrease in performance."

So as long as it performs normally, regular unleaded is OK.

I've been going through the same thing with a recent acquisition... So far have stuck to mid grade and premium.

 

[raytseng]

You can also just try it for a couple fillups, as it states it won't damage your car.

But before you decide, instead of just calculating Percentages you should also calculate the Absolute value of how much premium is going to cost you extra over a year but also compare it with your Total costs of ownership including fuel, vehicle taxes, insurance and so on. So total cost of ownership using regular=$X and total cost of ownership using Premium=$Y

When gas prices decrease, you put too much focus on the percentages; even though in absolute values it ends up costing you the same $250 increase for the year.

You may be putting in way too much focus on gas prices. This is an effect that we are over-exposed to gas prices as you see them multiple times per day and every few blocks with signs that are a foot tall, which you don't see with other goods.

 

[Ramblejam]

Originally Posted By: Kestas
What do you think?


Check out the Murano forums; consensus with your 2nd gen. and high(er) octane is a small increase in fuel economy (somewhat offsetting the initial additional expenditure), but a very significant boost in seat-of-the-pants performance.

 

[beast3300]

The VQ engine family has always suggested premium fuel. I'm sure nearly none of these vehicles receive it. Realistically the cost difference is not enough to deter the use of premium in my opinion. From what I remember in driving Murano's with the CVT is under light driving the engine is lugged around at very low RPMs. Without live data it is difficult to say with there is spark knock and therefore timing reduction.

You can always do 3 tanks of premium of the same fuel brand, station, and pump at that station then with regular fuel.

 

[benjy]

theres always mid grade 89. in colder weather with knock not being as possible lower octane may be similar to premium. todays ethanol laced fuels run cooler as well but giving less BTU aka power!

 

[Wolf359]

Originally Posted By: benjy
theres always mid grade 89. in colder weather with knock not being as possible lower octane may be similar to premium. todays ethanol laced fuels run cooler as well but giving less BTU aka power!


If you do the math, mid grade never makes sense. It's typically a mix regular and super. Here we have 93 super so I believe 1/3 super and 2/3rd regular gives you 89. You can also do 2/3 super at 93 to 1/3 regular to get 91. That's all they're basically doing at the pump, they just have two tanks, regular and premium and that's how they mix it to get 89.

 

[mclasser]

My Infiniti's fuel door also recommends premium, and that's what I use. The engine runs noticeably smoother so the extra few dollars at the pump are worth it.

 

[Olas]

I interpret the owners manual as saying

"87 as an absolute minimum, anything higher is better upto 98"

 

[bioburner]

Having driven an older car that said "high octane" the only time I could tell a difference was when I would let horses go an extended time getting things a bit toasty with intercooled twin turbos. Normal boring driving noticed nothing.

 

[Ramblejam]

Originally Posted By: Wolf359
If you do the math, mid grade never makes sense.

Say you have an engine that sees knock/pulls timing on 87, but with 89, it's effectively alleviated, and 93 offers no notable improvement.

Why would it not make sense in this scenario?

 

[ammolab]

At least they list AKI in the manual like on our gas pumps. Many..(most?) Lexas owners use Premium gas but the manual lists "91 RON octane" which is the European system and is equal to our Regular gas.

Here Premium can run 60 cents a gallon more than premium..that is a big waste of money through a Toyota engine!

 

[Wolf359]

Originally Posted By: Ramblejam
Originally Posted By: Wolf359
If you do the math, mid grade never makes sense.

Say you have an engine that sees knock/pulls timing on 87, but with 89, it's effectively alleviated, and 93 offers no notable improvement.

Why would it not make sense in this scenario?


Well if you did the math like I suggested, mid grade is typically more per gallon than just mixing in a few gallons of super with regular. For example, the local gas station is $2.10 for regular, $2.30 for plus and $2.50 for super. So you're basically paying for the equivalent of 90 when you're only getting 89. So if you need 18 gallons, 1/3 super and 2/3 regular would be $40.20 whereas plus would be $41.40. I don't know, is it worth the hassle to save $1.20?

 

[aquariuscsm]

My Nissan says "Premium Unleaded Fuel Required" on the fuel door and tachometer. I have to use it. With yours saying "recommended",you might be ok with regular unleaded.

 

[901Memphis]

I'd try the 89

 

[Hokiefyd]

I would bet you a coffee that there is an objective performance difference in that engine. Premium fuel comes with a premium price, and I doubt Nissan would have put the recommendation there if it didn't have merit.

Now, whether or not you can personally feel the difference in your particular vehicle, or whether you think it's worth it or not, is your call.

 

[WylieCoyote]

Originally Posted By: Ramblejam
Originally Posted By: Wolf359
If you do the math, mid grade never makes sense.

Say you have an engine that sees knock/pulls timing on 87, but with 89, it's effectively alleviated, and 93 offers no notable improvement.

Why would it not make sense in this scenario?



I'm getting low-rpm, light throttle knock in my '15 Canyon 3.6 on Quiktrip 87. 89 stopped it.

 

[kschachn]

And my BMW gas cap says 89 octane, so I think it makes sense for me.

 

[Kawiguy454]

IMO Your ECU will adapt to any fuel that causes a knock. The system can and does work so tooling down the highway @65 using 87 octane makes ZERO difference. However if you're towing a loaded trailer up a hill the premium will make a big difference which also happens to be where you're most likely to get engine knock.

 

[Hollow]

I have vehicle that states "Regular 87 or higher octane is required. Premium 91 or higher octane is recommended." I can tell the car pulls timing like crazy on 87 octane. It runs "fine" but the HP and MPG take a hit.