svarog

Hello,

I just bought my '95 Maxima GXE last week. After running a couple of 87-octane tanks through it, I cracked open the manual and discovered that it's supposed to take 91-octane. Whoops!

I did a search here on the board and I saw this has been discussed before. I also saw the FAQ article suggesting the loss in HP/torque on the Jetta with lower octane fuel.

But has anyone here specifically recorded a difference in fuel mileage (or power) in their Maxima depending on what type of fuel they run?

The Maxima clearly has a knock sensor, because I haven't heard any knocking. Also the manual says that 87-octane fuel is ok "if premium fuel is not available".

But even if you didn't care about power (which I do), it would be worth paying 10% more for premium if you get 10% better gas mileage.

I personally plan to start running premium after this tank -- so please no replies like "stop being cheap and buy premium beotch". I was just wondering if anyone here made the switch and actually noticed the mileage/power difference.

-Svarog

fearthegecko

yes.

When i got the car, i thought i could beat the whole premium thing, so i ran 87 for 2 or 3 tanks. then i switched to 93. The car ran better. It's hard to describe, but you could feel a change in the way it drove. I figured it was all in my mind....the placebo effect. so i ran the car dry, and tried one last tank of 87. then i could feel the car being sluggish. So i went back to 93, and have been ever since.

Another thing, if i run 93 from a texaco around here, i get a sulphur smell coming from the exhaust at times. I switched to sunocco's 93, and the smell has gone away. Also, if i run ultra 94, i can get over 300 miles to the tank, which i hardly ever see.

97max5spd

The octane rating is nothing more than a measure of how well the gasoline resists detonation. There is no real reason that you would get better mileage from using 93 octane fuel. What you will get is engine life (the knock sensor has to sense knocking before the computer changes the timing, at which point some damage has already been done) and the additional additives that are in most premium fuels that will keep your engine running well. Also, what most people dont realize is that knocking is only possible at higher engine loads (passing, towing, etc), so if you are not going to demand much of the engine while you're cruising on the highway, premium fuel is useless. So if you are driving your Maxima like an old lady, use the cheap stuff and put in a fuel system cleaner every time you get an oil change. If you get the urge to drive fast once in a while like me, go the safe route and use premium.

NastyNissan

It is very true that octane is just an additive that causes the gasoline to detonate (light off) at a higher cylinder pressure, but it occures not necessarily only at higher engine speeds. In truth, detonation can occur whenever the engine is under load...when you are accelerating, going up a hill, etc. I ran 1 tank of 87 through my car, but was experiencing detonation when I left the stoplight at a leasurely pace. After I filled the tank with 93, the detonation went away completely. I got 380 miles out of the 87 octane tank, and I expect that to be about the same with the 93. If you drive like a bat-out-of-hell all the time, you won't experience any milage benefits to the octane change, just long term longevity.

Spence

bolido2000

What are the thought on 89 Octane?

NastyNissan

It isn't as good as 93, but a little better than 87. Its a =only a couple bucks more to fill up with the good stuff...do it and you won't have to worry about replacing a blown head gasket or pistons later on down the road due to excessive detonation. Pay a little now, or a lot later.

Spence

ththcolumbus

iTrader: (1)

I have done this exact test with no change in fuel mileage. But, and this is a big but, I had to drive the car very easy on 87 octane. I could feel the engine surge when the computer changed the ignition timing because of knock. I stick with premium now because I always find a time where I give her all she's got. Remember that the cost of premium is a relative cost. I found a gas station that only raises 5 cents per grade. Now it's only $1.50 extra to fill my tank with premium. I drive a '97 SE w/5 spd.

By the way, I've averaged 27 mpg for the three years I've owned the car covering 90K miles. I can get 31/32 MPG on pure freeway driving.

- Jeff

SteVTEC

You're not ever going to hear knocking because the whole point of a knock sensor is to pick it up before you hear it and then tell the engine computer to backoff on the ignition timing so that it doesn't damage the engine.

If you do hear knocking then you probably have a bad coil, or your knock sensor is blown.

SteVTEC

When I was looking for Maxima's, I test drove a 98 or something and it had ZERO fuel in it. I watched as the salesman put 87 octane fuel in it. It was no surprise to me that the engine felt slow and sluggish. Going up this onramp pretty hard, the car felt like it had no power, and I couldn't even get this stupid Jetta off my tail. What a dog.

15 minutes later I'm at another dealership looking at a different 4G Maxima. Car was also bone dry on fuel but this time the salesman put 93 in it. OMG what a difference!! Same route, same roads, same onramp. Whereas the other one felt like a dog, this one literally ripped.


Still could have been a coincidence as there might have been something wrong with the other car, but I doubt it. The engine itself felt much more lively and responsive on premium gas - how it was designed to operate.


You can still get the same mileage with 87 octane if using a light foot, but when you put your foot down, or even if you have a heavy load of passengers, the engine just won't be running like it should. If you buy a Maxima and get the awesome VQ engine, you should just put the fuel in it that it was designed to operate on: 91/93. Otherwise go buy a Honduh

svarog

So in other words, with 87-octane you have to hit the gas harder to get even decent performance. More throttle = more gas used.. so I guess if you are definitely going to drive hard, 91-octane is better and probably gives better mileage under hard driving.

Oh, by the way, 91 is the highest octane you can get in CA. And here in S.F. it runs about $2.50 a gallon.

AssyrianRacer

I actually tried to record the actual Numbers, but got lazy but i got a uge loss in gass mileage with 87 octane... It did a little better with 93, but the best i found is when i mix 89, and 93 together.

Miasma

i was at a dealer (Audi) the other day. they do not recommend premium, they say that at altitude, 1Mi, higher octane leaves more carbon and is not benificial anyway. anyone want to comment on that? i know that higher altitude requires lower octane, but thats why all premium is 91 octane.

SteVTEC

Higher altitude has much thinner air, which reduces maximum cylinder pressures at WOT, which reduces overall power, which reduces the likelihood of experiencing detonation, which reduces the need for octane content in your fuel.


It says right in the Nissan manual that you don't need higher octane fuels in high altitude areas.

MacGyver265

I disagree. When you run 87 Octane, the spark is retarded to keep detonation from happening. When you do this, your engine loses some power because the spark happens either when the piston is at TDC or after it, and not before it. Especially at higher rpms this can be felt because the spark advance is particularly important at higher speeds. Its a trade off, would you rather buy 87, have your car run like crap, and then end up having to fuel up sooner? Or just put the good stuff in and fill up at slightly later intervals and end up spending the same amount of money?

On lower compression engines though, like a Chevy V8, running anthing better than 87 is a waste.

Str8ridin

What about pinging? I don't hear knocks, but I hear ctackling noises under acceleration. Is this knock sensor related?

btw, I use 91 or 93 octane.

fearthegecko

I thought one of the reasons for bad gas mileage could be poor timing. And since low octane gas causes knocking, and timing retardation, that if you run higher octance, you have less detontaion, less timing adjustment, and better gas mileage.

SteVTEC

You'll probably only be getting the timing pulled at heavy throttle or high-load conditions on 87 octane. If the engine is idling, or you're just cruising at very low power levels, 87 is probably fine. It's when you actually get on it when the cylinder pressures are higher that all hell breaks loose. The engine will start pinging, timing will get pulled, and you'll have less power than you normally would. Then because you have less power, you get on it even more. That complicates the problem, more pinging, more timing is pulled to compensate, and your engine is now running like complete crap. This is also what causes your fuel mileage to go south.


I get on it a lot (DC area, cut and thrust, heavy stop and go), so only 93 for me.