Pathfinder Higher octane fuel?

[0deuce0]

I noticed on nissanusa.com it says ...

"Use regular unleaded fuel with 87 octane. For maximum power, use premium fuel."

http://www.nissanusa.com/pathf....html

How many of you out there have ever noticed a difference between the two octanes... If any? Knocking / pinging from the engine? better / worse gas mileage?

[Buzzman]

I have an 02 Pathfinder and an 03 Sentra SE-R. Both user manuals tell me I should run premium gas.I did that when I first got the vehicles, but when the price of gas shot up 2 years ago, I started running regular gas....with no noticable differences. Both vehicles run the same, regardless of what level octane I use. Every once in a while I run a tank of premium gas, just to prove to myself that there is no difference. So far so good. I'd rather save the money and run regular.

[Pisspi]

I used a tank of 91 octane then a tank of 87 and I didn't notice any difference in mileage, knocking or acceleration other than my wallet.

[KoukiS14]

On the fuel door of my 97 240sx, it says "Premium Recommended...." Honestly, I notice no performance differences in any area when I use it.

I mean c'mon. . it's a KA. :o

I feel the same about my QX4. . it's a truck engine. The VQ I thought was supposed to require premium, so this is (good) news to me.

[Acey]

With a higher compression motor and cheaper gas, the timing retards to the point to where it won't ping. The power loss will only be felt at higher RPMs under throttle. In ordinary driving, you will not notice a difference.

[vliou]

I've done the math...

You get better mileage with premium...it turns out to be roughly the same. Treat your car better...in the end, you spend about the same amount of money anyways...

With the premium fuel, shell offers detergent gasoline which cleans carbon deposits, so that saves you fuel injector cleaning anyways.

In the end, it balances out...i spent a good 2 months on this!!!

[nissandoms47]

it also depends on your altitude. if it calls for 91 or w/e at sea level it'll just need 87 at say 4-5k feet. My 96 pathfinder calls for 87 octane, i just put 85 in it because im at like 5500ft. im sure if i put 87 in ill get a bit more power but it wont be noticeable.

[fueler]

I've done the math...

You get better mileage with premium...it turns out to be roughly the same. Treat your car better...in the end, you spend about the same amount of money anyways...

With the premium fuel, shell offers detergent gasoline which cleans carbon deposits, so that saves you fuel injector cleaning anyways.

In the end, it balances out...i spent a good 2 months on this!!!

Better mileage with premium - this is not true. Octane is the measurement of a fuels resistance to pre-detonation, meaning a fuel with a higher octane has less of a tendency to combust simply under compression, because the fuel SHOULD be sparked by a spark plug. The computer in your car will sense how efficiently the fuel is burning, and adjust the timing to compensate. At higher octanes, the ECU is adding to the timing, effectively giving you slightly LESS gas mileage. The difference is so small, that gas mileage is either unchanged or reduced at higher octanes. No way is it possible to get better gas mileage with a higher octane. Have you tested your theory yet?

[nissandoms47]

Better mileage with premium - this is not true. Octane is the measurement of a fuels resistance to pre-detonation, meaning a fuel with a higher octane has less of a tendency to combust simply under compression, because the fuel SHOULD be sparked by a spark plug. The computer in your car will sense how efficiently the fuel is burning, and adjust the timing to compensate. At higher octanes, the ECU is adding to the timing, effectively giving you slightly LESS gas mileage. The difference is so small, that gas mileage is either unchanged or reduced at higher octanes. No way is it possible to get better gas mileage with a higher octane. Have you tested your theory yet?

How is that true? The computer senses how much fuel to dump in too, trying to create the best Air to Fuel mix ratio. If that ratio is screwed up by putting in lower octane fuel that does not combust properly it'll reduce gas mileage. So just stick with what ever the users manual says.. 87 for the VG33Es and 91-93 for the VQ35DEs.

[vliou]

In fact, I have! 12.7mpg with premium, 10.3 with regular...

[KoukiS14]

I just use diesel since it's better mpg.

[fueler]

How is that true? The computer senses how much fuel to dump in too, trying to create the best Air to Fuel mix ratio. If that ratio is screwed up by putting in lower octane fuel that does not combust properly it'll reduce gas mileage. So just stick with what ever the users manual says.. 87 for the VG33Es and 91-93 for the VQ35DEs.

Read again: Octane is measurement of a fuels resistance to detonation. Higher octane fuels require more to burn AKA the higher the number, the harder it is to combust that fuel. This is for high compression or forced induction motors so the fuel doesn't detonate early, causing a misfire or pinging. You are right about the computer sensing how much fuel to dump in - it does exactly that, at higher octanes it needs to dump more fuel to compensate for it!!! Quoted from Wikipedia http://en.wikipedia.org/wiki/Octane_rating "It might seem odd that fuels with higher octane ratings explode less easily, yet are popularly thought of as more powerful. The misunderstanding is caused by confusing the ability of the fuel to resist compression detonation as opposed to the ability of the fuel to burn (combustion). "

[fueler]

Also from Wikipedia: Octane rating has no direct impact on the deflagration (burn) of the air/fuel mixture in the combustion chamber. Other properties of gasoline and engine design account for the manner at which deflagration takes place. In other words, the flame speed of a normally iginted mixture is not directly connected to octane rating. Deflagration is the type of combustion that constitues the normal burn. Detonation is a different type of combustion and this is to be avoided in spark ignited gasoline engines. Octane rating is a measure of detonation resistance, not deflagration characteristics.

I guess I was wrong too!

[nissandoms47]

But for an engine that requires 91-93 (high octane), it would be bad to put in anything less at sea level. Or else it combusts prematurely or even out of the combustion chamber causing backfire, knock etc.. So just stick with the users manual.

VG33Es take 87

VQ35DEs take 91

[Buzzman]

If I understand what you are saying correctly, then if I run 87 octane in my vq35 Pathfinder, then it's going to knock, ping, and backfire and possibly damage my engine?C'mon now. I don't know the gas prices in the states, but up here (Canada) it's about 10 cents more for a litre of premium gas. That translates into at least 5 bucks more per fillup. I've run 87 octane for years, and still stand by the fact that there has been no noticable difference in all that time. Considering the poor mileage this engine gets even at the best of times, 5 bucks every few days adds up to a lot of savings.

[nissandoms47]

Please reread my post. I said at sealevel, since you're above sealevel (im assuming since you're in Canada) then 87 is fine. And seriously people, its just gas and its just a pathfinder. Pathfinder= SUV, It might get a little pissed if you put the wrong gas in but it really doesnt matter. Its no race car. But ive seen some people do some really crazy things to their pathfinders..

[Acey]

Your VQ35 will automatically retard the timing to prevent detonation and decrease performance slightly with low octane gas. This is why you have a knock sensor. If you are trouncing on the throttle and taching it out all the time, higher octane will be slightly more efficient and produce a little more power. But, if you are doing that, you aren't going to get accurate stable milage readings anyway. Under heavier load and higher RMS when the timing is at it's most advanced is the only time higher octane makes a difference. Under normal driving, you shouldn't see a difference.

[Buzzman]

Thanks for the feedback. Sounds like driving habits have a lot to do with how these things perform. I don't drive mine like a race car, that's for sure. I have my SE-R for that. I also don't haul heavy loads or go off roading. I originally bought this truck for 2 reasons. 4 wheel drive in the winter, and I needed something to haul my tools and stuff around with. I'm very happy with it.FYI: Where I live is only about 300 feet above sea level. Still, the truck runs fine on regular gas.

[nissandoms47]

Is it humid where you live? lol, im just throwing stuff out now.. But seriously, if you wanna get good gas, dont buy a pathfinder.

[Buzzman]

The weather extremes here do play a part in gas mileage. In the winter it's cold, and dry as a fart. In summer, it swings the other way and we have hot weather and 90% humidity. The car runs great in May and October (just kidding). Yeah, I didn't buy my Pathfinder to save money on gas, that's for sure, but I didn't realize it would be that poor either. Oh well, that's life.

[nissandoms47]

lol, my gas mileage will go down when i put on my 33s or 34s.