martinf

My owner's manual recommends octane fuel "of at least 91".
Premium is recommended, but "regular 87 can be used"
There is no 91 gas here, only 87 90 and 93. Should I be going up to 93?
Martin
5sp SE

2000MaximaSE

Yes, use 93
We used to get 94 here but i cant find it anymore... Now its 92 for me

Adam

CIRCO

iTrader: (1)

You should be using PREMIUM gas to avoid any knocks, pings and anything of that sort. Also to put your sig on go to profile. It will prompt to a screen then just scroll down to signature.

y2kse

iTrader: (1)

But my wife has run 89 octane in her 2K GXE for over 18,000 miles without a single hiccup or ping.

tomz17

No NO NO NO NO NO NO NO NO... you are doing your car a GREAT injustice!!

It was designed for 91, give it 91... the kock sensor will allow it to work correctly with lower octanes, TEMPORARILY, but it is not a PERMANENT solution.. Don't use lower octane fuels.. You CAN cause damage this way!!

91 is ideal

anything more than 91 is fine as well..

FYI -> you can mix equal amounts of 93 and 89 to make 91!!!

tomz17

Actually IMHO, using anything less than 91 does run the risk of damaging your engine.. Especially over time!!

Chances are your car does "ping" (even though you may not be able to hear it). Nissan recommends 91 for a reason (if they could don't you think they would say "go ahead use 87"!!!?? --> sorta like Saturn does?? Saturn's big thing is "Our cars run on nothing BUT regular gas!!"

Just my two cents...

tomz17

Well from what I understand (from this forum, and other sources) Engines [especially higher performance engines]are specifically tuned to run at peak efficiency on certain octanes, by achieving precise timings during combustion. (There's a lot of Math, Physics AND Chem involved here.. most of which escapes me at the moment)

Changing your Maxima's octane would therefore affect this timing (since as you imply, there is a difference in volatility between octanes...)

{actually, on a side note :: its a tad more complicated, because it turns out that the octane rating is a factor in determining the ability of unburnt end gases to resist spontaneous autoignition -> which has a very direct physical relevance to the way any combustion engine works}

Anyhow, I am led to believe that Nissan apparently understands that it's not a perfect world, and that all engines will knock, regardless of octane.. So they include a knock sensor, which should (based on detected knocks), retard engine timing to compensate..

I have also been led to believe that the knock sensor should not be used as a permanent solution which would allow one to use lower octane fuels in their Maxima..

I may be wrong, but no I am not pulling any of this info out of my a$$... just going on stuff I know, and have read previously.. It also seems counter-intuitive that Nissan would insist we use 91 octane fuel, if in fact, we COULD safely use 89 or 87!!.. I mean, especially with gas prices so high over here, and around the world!!!

Guest

your right. Putting 87 octane gas and letting your engine knock is not a solution. As in the FAQ page in the website, A knock senser detects knock, which means the knock already took place which will destroy your engine, and all it will do is to retard timming. Just stick with 91+ octane. Follow the Factory manual because no one knows your maxima like Nissan.

y2kse

iTrader: (1)

From http://netnow.micron.net/~marriott/gasoline.htm :

"If you use a fuel with an octane rating below the requirement of the engine, the management system may move the engine settings into an area of less efficient combustion, resulting in reduced power and reduced fuel economy. You will be losing both money and driveability. If you use a fuel with an octane rating higher than what the engine can use, you are just wasting money by paying for octane that you can not utilise. Forget the stories about higher octanes having superior additive packages - they do not. If your vehicle does not have a knock sensor, then using an octane significantly below the requirement means that the little men with hammers will gleefully pummel your engine to pieces."

"You should initially be guided by the vehicle manufacturer's recommendations, however you can experiment, as the variations in vehicle tolerances can mean that Octane Number Requirement for a given vehicle model can range over 6 Octane Numbers. Caution should be used, and remember to compensate if the conditions change, such as carrying more people or driving in different ambient conditions. You can often reduce the octane of the fuel you use in winter because the temperature decrease and possible humidity changes may significantly reduce the octane requirement of the engine."

"Use the octane that provides cost-effective driveability and performance, using anything more is waste of money, and anything less could result in an unscheduled, expensive visit to your mechanic."

wdave

I tested this on an earlier Maxima. I ran several tanks of each octane,87,89,93. There was a noticeable driveability difference at each level. The amazing thing was that the mileage changed by the same percentage as the difference in price between the grades. Conclusion - not worth running the low octane even if potential damage is not an issue. BTW that was a few years ago, the percent difference in price between grades is less these days so higher octane could actually end up cheaper.

Dave

Maxima-Ness

I noticed the difference right off the bat when I first got my Maxima. The dealership of course gave me my first tank of gas free (they used 92 octane). I was like most people and just went for the cheapest gas when i pulled up to the gas station for the second fill up. I imediately noticed that I lost that "go" factor that I had before. It didnt occur to me that it was the octane rating causing this, but I quickly wised up to it and now only use the premium, no matter how much it costs! and my car is one thirst B*tch :-)

wdave

You have the car, go ahead. I have seen it on the chassis dyno I owned, and had enough experience over the years to know that octane is octane and most of the rest is myth. The determining factor is how far the spark will advance given high enough octane, that limits the benefit. I doubt that the Max goes much beyond the advance for 91 , most likely 94 or 99 would do nothing.
In the "old" days you could play with timing. I did. I also replaced a lot of pistons. I wouldn't run wot on my Max with 87 octane. 89 is close to the recommendation but if you check mileage and crunch the numbers you'll se it doesn't save $ over 93.
Incidentally, Click and Clack addressed this very issue on "Car Talk" about three weeks ago.

Dave

tomz17

Bah Humbug...

My baby drinks the good stuff... Why would you buy a $20+k car and then pinch pennies on gasoline.