JMaster

I usually use 91, but my friends insist that 87 is fine. What do you think?

Eleebob7

91 is what the "dealer recommends" but it's usually a load of garbage. In the max, the engine can't efficiently use the high octane and in some cases causes a loss in power. I don't know where the article was but they filled a BMW and I think a Mustang with the different octanes and the mustang lost power. So I have a feeling it's the same with the Maxima. I tried it with 91, and noticed no difference. Just save your money and use 87

Wreck-Diver

I only use 93. When I picked up my car from the dealer, new, they had 89 or something in it, and it knocked a bit while at idol, shifting into gear. Havent had a problem since. Good luck!

UMD_MaxSE

iTrader: (1)

i dont think so....

RACEFACE

Petro-Canada 94 here.

WILLSE

93 no less

will

StygianMax

iTrader: (8)

Some engines engines perform best using highest octane gas....but not all manufacturers'! A friend of mine who's buddy works in one of GM's engineering depts. said some GMs don't even like high octane gas & that they run best with 87. I don't know the chemistry side of it but it relates to combustion. I think the higher the octane#, the greater the consistency in carbon molecule chain lengths (like a homogeneous mixture). The lower the number, the more you have those carbon molecule chains of different lengths. Sorry, I can't elaborate any better than that! I'm sure you can find the details on the Net somewhere.

hokiemax

iTrader: (2)

OMG. what are you smoking dude?

If you can't feel the difference between 87 and 93, have your butt dyno calibrated. Knocking is bad for your car. I put in 87 in my bro's car, and it pinged bad..

I'm sorry for the offensive tone, but I feel this is of utmost importance.

MONTE 01&97 SE

iTrader: (1)

Yes with 87 Maximas are known for pinging, I use 91 or 93 Octane. Why not use the best, since most of us care about performance!

y2KAOSMax

I mainly use 93 or 94. Sometimes I use 100 , but never 89 or 87..

SteVTEC

No, it's actually what NISSAN ENGINEERING recommends because they're the ones that designed the engines.

Wrong. The opposite is the truth. The VQ REQUIRES the higher octane and will lose power on LOWER octane.

Car & Driver, November 01. And they never tested a Maxima.



The Maxima's ignition timing is tuned for 91+ octane fuel, and the compression ratio (10.0:1) is high enough that higher octane fuel is required to prevent knocking. If you use lower octane fuel, the engine will start knocking, the knock sensor will detect that, and then send codes back to the ECU telling it to retard the timing to prevent the knocking. The the timing will be off and you'll lose power, but at least then the engine won't be knocking.

The octane requirements of an engine are most directly related to the COMPRESSION RATIO of the engine. The rule of thumb is that if you have a 9.xx:1 CR or lower engine, you can usually get by with 87. If you have an engine with a 10.0:1 CR or higher, you'll most likely need 91 for best performance.

My Accord V6 had a 9.4:1 CR and hence only required 87. If you put in higher, the ignition timing would be thrown off because of the different burn rate of the higher octane fuel (requires more ignition advance) and hence the lost power in that C&D test.

Maxima's run a 10.0:1 or higher CR and require 91 octane.

My fiance's Toyota Highlander has a 10.5:1 CR. The book says it's okay to use 87, but also notes that 91 should be used for best performance. The performance on that 3900lb SUV is clearly MUCH better on 91+ gas than on 87. The 91+ gas allows more ignition advance and more optimal timing and gives MUCH better power.

So you live at high altitude, right? That's the ONLY place where you could get away with 87 in a car that requires 91 and not lose performance. The thinner air effectively drops the compression ratio such that the higher octane fuel is no longer needed.

SteVTEC

I think your friends don't understand how engines work and what octane levels really mean.

Also, try searching. There have been MANY threads on this subject

Myrv

Ok, the first thing to remember is the octane rating of fuel has absolutely nothing to do with its power. The octane rating is merely an indication of how well the fuel resists premature ignition (aka knocking or pinging). It has nothing to do with energy content of the fuel. Case in point is ethanol. Ethanol has a very high octane rating compared to gasoline but it's energy content is only about 84,000 btu per gallon compared to 115,000 btu (or 125,000 according to a different source) for gasoline. Ever wonder why Sunoco sells 94 octane premium? It's because they always use ethonal in their fuel. You'll only get 111,000 btu per gallon out of it though.

So why do we want higher octane fuels?
Glad you asked.

You see, with a higher octane fuel you can increase the compression ratio of your engine without having to worry about knock. The higher compression an ngine is, the more efficient (think diesel) it is and the more power it produces. The 5th gen Maxima engine has a 10:1 compression ratio (10.3:1 for the 3.5L) which is slightly higher than the average 9:1 to 9.5:1 ratio most cars have. This is why they recommend 91 octane fuel in the Max.

But your friend drives with 87 without any problems you say?

Well there's a couple of explanations for this. First of all the Max is equiped with a knock sensor. If you put lower octane fuel in and the engine starts to knock the computer automatically retards the timming. This stops the knocking but robs the engine of power and may cause some long term buildup of deposits. If they are not pushing the car the average driver will probably not notice the drop in power though. Another reason is that if your friend lives in Denver then the lower air pressure (due to the altitude) lowers the effective compression of the engine and lower octane fuels are fine, in fact prefered.

What about that Mustang that lost power with higher octane gas?

Well that could very well be true. If the engine is not designed with higher octane fuel in mind then you could very well lose power by putting it in. This comes back to my fist paragraph were I mentioned it is common for higher octane fuels to actually have a lower energy content per unit volume than lower octane fuels. If the Mustang doesn't knock with 87 in it then you are just losing energy by going higher. Note though that the performance gains of a higher compression engine outweigh the loss due to lower energy content in the fuel.

Which finally brings us to those who use greater than 91 in their Maxima's. Does it give them any advantage? Probably not (at least not from the octane point of view). I say probably though because if you drive the car really really hard you can induce knocking so if you autocross or dragrace a higher octane fuel could be beneficial.

That all said I'm guilty myself of putting 92 octane it mine. Do I need it? No. But it makes me feel good

rntmax02

I only ever use 93-94 depending on the brand. The only othe choice we have is 87 or 90 and if you read your manual we a require a minimum of 91. Think about it why would they put that in if it didn't matter. They don't make any more money by you using 91 or higher.They put it in because that is what it is designed for.

maximadave

iTrader: (10)

91 octane Chevron Super Unleaded

100 octane Unocal 76 racing fuel on occasion

SteVTEC

This will only hurt your performance, unless you have a SERIOUS amount of boost or N2O.

2kmaxse

In order to fully grasp the concept. U must become one with your baby and being the Maxima ethusiast that u r, this should be a no question to go w/ 93 or 94. If u look at it you r only saving a buck or two on a tank, why not go w/ better ****, and feel the tickle in your belly when on take off!!!!!!

SUNOCO 93 or 94 when feeling a little rich....

2k2Merlot

I always use the highest grade available at the station I fill up at. Usually Chevron or Texaco.

Anuj

I use 93 from Mobil or Exxon. I put this in my car because it gives better miles to the gallon. Also I read somewhere about the ignition and octanes so I don't want to take a chance on this great car.

Maxima06071

I completely agree, Today I switched to premium.
The reason: I was driving up the hill out of my neighborhood and not wanting to get passed on my right by an older Camaro I floored it....then..nothing.
Man my car felt doggy, realllly doggy!
I decided to see if a better(more expensive fuel would help) well it did I used some Chevron Super Techtron and my car drove brilliantly!
Problem solved it accelerated much better reved to the redline( or close to it, I'm an AUTO) with full song. I was so happy I'm never using anything under 92 octane again!
I got huge smile after this awesome "mod".

Step2kMax

With old car (vw jetta-3) 87 worked fine. But, 4 cyl./110hp. With 2K-SE, i'll stick with 93 oct. BTW, try to gas up on tues. or weds. when prices are most likely at there lowest.

maximadave

iTrader: (10)

At the Unocal 76 I only put about 4-5 gallons of the 100 octane and mix it with 91 super unleaded.