AirPilot8004

Got a couple quick questions on gas for my Max.

1) What type should really be in the tank? 87? 89? 93? What does Nissan recommend? What do YOU recommend? Why?

2) Truth be told I am a poor college student and switch back between 87 and 89 or 93. I have been told that this is bad for the engine?

3) In your own opinion, do all gas stations pretty much have the same gas? I have heard that certain people only go to certain gas stations to get certain grades? What's your take on that?

I appericate any input or insight can give me into this dilemma of mine.

endus

iTrader: (1)

Run what is in the manual...91. The car will run on lower octane but will not have full power and fuel efficiency.

I run only Sunoco and only Ultra 94 which is now "Ultra" 93...I am wasting my money....and I'm fine with that. The Ultra 94 used to be different and there was some evidence that it left your plugs a little cleaner, but I don't think that's the case with the "Ultra" 93.

sagemistse

do they sell ultra 94 anymore?? I was at sunoco the other day and all I saw was ultra 93

Kevlo911

iTrader: (36)

91+ You get better MPG and actually SAVE money because of hte better MPG with 91+ compared to 87

Dave B

1) Run the recommended octane of 91. The Maixma will run on the lower octanes, but the ECU has to dial back timing/advance and usually this will result in a a 5-10% reduction of power and MPG. For the amount you save getting lower octane fuel, you'll spend more on gas because the car is getting worse MPG.

2) Octane ratings have nothing to do with fuel cleaness. All fuels are clean and contain additives for a clean running, the only difference is octane.

3) Higher octane fuels are less explosive. Octane is a measure of resistance to preignition (ie detonation) and a general resistance to burn. The VQ in the 95+ Maxima has a relatively high compression ratio therefore it needs a higher octane fuel that won't preignite under the extreme heat of high compression.

4) Shell/Amoco/BP/Conoco/Phillips 66/Mobil/etc (big name oil companies) all have bascially the grade fuel and quality. It's just a matter of choice. IMO, stay away from the mom/pops gas stations because their storage tanks could be corroded and have small amounts of water in them. I wouldn't recommend getting fuel from Costco or other cheap gas outlets because these fuels typically have higher concentrations of ethanol (corn oil) which means the fuel has less energy per gallon therefore worse MPG.


Dave

DAVE Sz

iTrader: (2)

Like Dave's SIG says, READ THE STICKIES and the FAQ.

VIP Maxima

if u really cant afford it. fill up with 87 but make sure u do a full fill up of 91 after every 3-4 tanks of 87 just to make sure the KS wont die and the engine gets what it needs. like they said, with 87, u still aint saving money.

and i will never understand why you guys make a big deal out of this. i mean, how much is the difference? in a FULL tank, ur spending $3.50 more with 93. its not like we talkin about $20 difference. think about the money you waste by doing other stuff. for example, how many days a week you waste your money on fast food? cigars? and i think this is a good example: we all buy bottled drinks from those vending machines right? well guess what, everytime you buy one, your spending 50-60 cents more than what you would pay at a regular store. 4-5 drinks a week(thats how many i buy when im at school) and there goes the money you coulda spend on the 91 octane.

so what im saying is that some people become "cheap" when it comes down to gas but then they waste their money on SOOOOOOOO many other things.

Brudaddy

iTrader: (2)

1. of the three you listed, you should use 93. The manual recommends that you only use 91, but I cannot get 91 here....only the ones you listed.

2. I am not just rolling in the dough, but it is worth it. I don't think it is bad for the engine to switch, but it would probably be better to just use 91+ octane alone.

3. All gas stations have pretty much the same gas. It is regulated and inspected by the government. However, Dave B was right when he said that stuff about the mom and pop places with water or other stuff in the gas. Pretty much, if you go to a place that gets a lot of traffic, you should be okay, because the tanks are emptied out pretty often.

I do think you will get better gas mileage with the 91+ octane, because it happened to me. However, I must be truthfull....if it does outweigh the extra cost of premium, it will barely do so. You do save some....let me demonstrate.
Before, I was using 87 octane and I was getting like 20-21 mpg. Well, I started using 93 and I am now getting 23-24 mpg. That is about a 2mpg savings.
Well, 2mpg better x 18 gallons in a fillup=36miles
36miles divided by 23.5(mpg on average) = 1.53 gallons of gas
1.53 gallons x $2.05 for premium = $3.14 savings

COST TO FILL UP WITH PREMIUM: $36.90
COST TO FILL UP WITH REGULAR: $34.02
......................DIFFERENCE......: $2.88 more to use premium than regular

That means you actually save $. 26 every fillup with premium....if your values were as I stated.

That looks correct to me, but check the values, everyone....ha ha. I need some food in me....ha ha....getting hazy...I may be totally off base here.

fishpony

iTrader: (2)

is there anything wrong with ethanol? the midgrade gas in my area has 10% ethanol. am i better just using the 87?

DAVE Sz

iTrader: (2)

Every gas station SHOULD have 10% ethonol. It's been like that for years.

maxNYC

iTrader: (1)

i run 91+ octane to keep the engine running clean

MAXRB8

iTrader: (19)

Absolutely 91+, I can feel the difference even between 92 & 94 and we pay approx $1.00 per gallon more in Canada. If you can't afford the extra $3.00 between regular and premium, drive some other piece of crap and spend more in repairs. The manual says 91+ eventually you'll pay the price somewhere be it at the pump or at the repair shop it's up to you.

bk-99-se-l

all gas is the same. i parked by a filling station one day at work. every big name company came and filled up from the same supply. only differance was the different octanes.(one truck for 87 one for 93 ect.)

Eric425

I get where you're coming from. I'm a college student too, and although people say that it's not a big deal to get premium since it's only a few bucks difference, it'll seem like a big deal to you when you're already overbudget for gas and you have to pay out even more to get premium. When you're feeling like you're overcharged, nobody gets happy when they ask even for a little more.

I personally started filling up with 87 when the prices broke 2.25 a gal. There hasn't been any noticeable reduction in fuel economy, so I'm happy. If there is a reduction in power, it's not overly drastic, so that doesn't bug me either. Besides, the maxima is now my slow, winter/bad weather car anyways. (Yeah, I'm a poorer college student, but I met a great deal on a mildly modded '00 z28 SS for just under 9k, and I had to jump on it. 400 hp, and torque to match. So sue me)

guido32

Dave B's right. Pre detonation = bad news. Its very unlikely, thanks to knock sensors, but why risk it? Besides, the more expensive gas gets, the more viable it is to buy premium anyway because the percentage difference in cost decreases.

mteller

Guido's right. A few people have talked about gas prices going up and switching to lower grade because of it. The truth is, the higher the prices go, the more economical it gets to buy premium. When prices were 1.00 a gallon you paid a 20% premium for 93 octane. Now that they are around 2.00 you only pay a 10% premium. When prices go back down is the time to wonder if premium gas is worth it.

Max96LSU

another FYI, when you do get gas, DO NOT pump gas when the truck is at the station or just leaving a station.. The reason for this is that when they are filling the tanks, sediment and crap that builds up on the bottom of the tanks get mixed around with the gas which later gets pumped into your cars.. This is the reason for the fuel filter. You can avoid having more serious problems by keeping a look out when you go to pump gas.

BTW, I use only 91+ octane

Dave B

Yep, good point. I even have my wife trained on that one.


Dave

Dave B

What kind of "big" companies are you talking about? I'm a contractor for various oil companies and I do work at the dispensing terminals. Sinclair Oil distributes their oil to smaller gas stations like 7-11, Quik Trip, Hy Vee grocery stores, Costco, Casey's General Store, and Sinclair. IMO, that's the crap gas I stay away from because of it's high ethanol content. Amoco/BP, Phillips 66, Shell, etc have their own specific terminals and only fill their own marked trucks. They also have their own refineries so that leads me to believe that they blend their own fuels.


Dave

maxburst

Let's see...$4500 for a new engine or a couple of bucks more at the pump. I'll let you do the math....

MidwestMaX1

Don't go cheap when buying gas. Not only do you get better gas mileage, but the car pulls harder with a higher octane (at least that's how it feels to me). I just bought some 92 octane and my car pulls harder than it ever has.

Brudaddy

iTrader: (2)

I think more than just getting worse gas mileage, the lower octane can do a lot worse stuff that you might not be thinking about.

I know that someone on here has already mentioned the fact about it making your knock sensor go bad. Well, that would be at least $100 to replace, if you found a good deal.

Also, when I was using 87 for a long time, my car started missing, like one of the coil packs was bad. Well, after about 3 tanks of the 91+, and a new fuel filter, it is running as good as it can. I mean, it pulls hard, and does not hesitate.

It just helps your car to run the best that it can. It is meant for the 91+, although it technically "can" run on the 87. Nissan designed it that way.

On the note of higher octain...yes, it does pull harder with higher octane....to an extent. For our NA cars, it will not really pull any harder with 93+ than it does with 91. You only get real benefits from very high octane gas if you are boosted, or NASCAR. ha ha ha

Eric425

The engines in these cars are cheap as dirt. You can find a replacement engine in good shape for $300. If you don't know something, don't just go making up numbers. Regular definately won't destroy your car. The ECU will run less timing advance. If you do want max power, they are designed to perform optimally when 91 octane is used. That's the reason to run premium.
Out of curiosity, Brudaddy, how does ping/knock ruin the knock sensor? The KS relays back a certain voltage to the ECU, and that voltage can be thrown off by vibrations, right? So how would that ruin the KS? In my mind, I'm picturing something like copper conductors, and when vibration is picked up, the electrical current is between them is stopped. So kind of like hitting the off switch on a light. I'm certain the electrical wiring in my household isn't damaged when I turn the juice off. So how does the KS get damaged by picking up ping/knock? Or am I picturing it wrong?

car_boy_16

That's a good way to demonstrate a point...People can talk all they want but until numbers are excersized to paint a financial picture, we wont get anywhere...Thanks, Brudaddy

car_boy_16

On another note, as fuel grades increase (87, 90, 93 or 87, 89, 91/92 - whatever) each grade shows an average of 5-8% increase in price based onlowest octane price.
Example:
87 Octane ~ $2.009 (5% of that equals 10.9 cents)
89/90 Octane ~ $2.109-$2.169
91-93 Octane ~ $2.209-$2.329

At 15 Gallons per fill-up, this is how it comes out.
*Regular Unleaded = $30.135
*Premium = $31.635-$32.535 = 4.8%-7.4% over Regular Unleaded
*Super/Ultra/Supra = $33.135-$34.935 = 9.1%-13.7% over Regular Unleaded

MPG increase? That is a very fluctuous variable that is REALLY hard to calculate due to many untolds. One is the 'Driving Spirit' variable, which (Im making this variable up as you probly know) can skew the calculations due to power increase when using higher octane which cancels out the KS signal, advancing timing to the ideal place (in the eyes of the ECU) causing full power to be unleashed, which all-in-all cuases the driver to drive more spirited, and finally reducing MPG consciously or unconsciously.

So let's just say 10-15% increase in MPG, and ~10-15% increase in power from using higher octane fuel grades that don't cause to the KS to activate.
20mpg*10% gain (1.1)=22mpg (or 23mpg with 15%)

20mpg*15gallons= 300 MPT (miles per tank)
22mpg*15= 330 MPT
23mpg*15= 345 MPT

SO 3mpg increase over the 20mpg with KS activation saves you about 45miles and at 23mpg that equates to just under 2 gallons saved per fill-up over 20mpg on Regular unleaded and at 10-15% power loss. Which is about 4-5bucks every week (depending on how much you driver per week).
I think it's well worth it.

DAVE Sz

iTrader: (2)

I couldn't disagree more.