Anyone use 89(Plus) grade fuel instead of 91(premium) or above fuel? I got a 2007 g35x 4dr sedan AWD. Mileage: around 118,000. I usually put Premium gas 91 or 93. But my cousin's friend own the same type of vehicle and he been using 89 (Plus) for about a year without having any problems. So, I was wondering what you guys would recommend?

Thank you.

 

While there is PLENTY of info on the internet about how fuel works, I'll try to explain this as simply as possible:

If you add a '0' to the end of any grade of fuel you essentially have the temperature at which it combusts under pressure. So 87 will combust at 870 degrees (or thereabouts), 89 will combust at 890, 91 at 910 and so on. So, in an internal combustion engine you want the gas to be ignited by your spark plugs before it naturally combusts (otherwise you get pre-detonation), otherwise you get "knocks" and "pings". Your cars spark plug ignition is controlled by the "timing" that was set by the factory. The timing is based on the temperature at which the gas naturally combusts. So, ideally, you want a fuel that will refrain from cumbusting on it's own, and last in the cylinder until the spark plug can burn it. The factory had "set" your cars computer to detonate just before it reaches 910 degrees. Following?

Now, in the old days, you would have to manually adjust your detonation timing any time you changed grades of fuel, but these days we have sophisticated computers in our cars that recognise predetonation and "pull back" detonation timing to adjust it automatically (based on temperature). What that means to you ultimately is that your cars computer will adjust to any grade of gasoline that you put in it and it will run perfectly fine and safe.

HOWEVER! the reason that Infiniti recommends 91+ is because that's what they designed it for, so when you use a different grade of gas and it "pulls timing" to adjust itself, you will not get the HP, longevity and/or MPG that Infiniti advertised, because that's not what the system was designed to run on. So, run any gas you want and you'll be fine, but you have to ask yourself if it's worth it to save $1 to essentially experiment with something that's not proven.

 

Great points ^

Loss in gas mileage makes using mid grade a waste.

 

Only use regular 87 octane. 171796 miles on my previous 06 G35 6 speed manual and 84.6k miles on my current 2012 G37S 6 speed.
No issues using regular. Substantial savings on fuel.

I generally use Love's regular at their travel plaza's when on road trips.



I use WaWa regular 87 for local driving





Telcoman

 

I totally expected to hear this from someone using low octane gas from a cheap quality gas station/company! Funny part is they're proud of their accomplishments. Stay with what Nissan recommends, if you want to experience the best of what you drive!
Gary

 

Yea I'm with Gary on this one. Premium only. I'm assuming that's why Nissan/Infiniti says premium only?

 

It says REQUIRED not recommended. So you can't really get away with it.

 

You should have bought an Altima if you wanted to save $2-$3 a fill up to use regular.

 

The extra pennies for premium don't come out of my fuel budget. They come from the entertainment budget....



And relative to what Scraggle says, from the maintenance budget. Why take chances?

 

The wife has one!

At my last fill-up at my local WaWa station premium 93 was $.50/gallon higher than regular 87 octane. Thus far since my August 2012 purchase I've used 3643 gallons of regular 87 Octane at 84356 miles. At a $.50/gallon savings, I've saved roughly $1821.00

On my previous 06 G35 with the 171796 miles, I used 7170 gallons of regular 87 octane except for my one month testing of using 91 octane and a one month test of using 93 octane. In both monthly tests I discovered that I got better MPG with no noticeable difference in performance. I'll use a $.40/gallon savings which equates to a savings of $2868.00. On these two Infiniti's that I've owned I've saved $4689.00 on fuel in almost 12 years.

Now I realize that there are many Infiniti owners that have so much money that they don't mind spending the extra money on fuel. Many also spend thousands on Mods.
Some spend unneeded funds on cheap aftermarket replacement parts most likely made in China that do not solve their problem so they come here asking questions of what could be wrong and what should they do never having read the FSM.
All of this makes for very amusing reading.

I have better uses for my fuel savings.







A well aged porterhouse steak beats wasting money on 93 Octane any day





Cheers

Telcoman

 

I agree mostly,,, when I KNOW I'm just gonna commute, I use reg. when I know I am gonna be hard on the car, ( autox, drag racing, and some high speed runs, i'll use prem. imo, a steady 65-80 mph, on the freeway, I don't see how u would need premium, or say across a big state like Kansas, on a road trip. the engine just isn't doing anything, just loafing along....

 

Of course if you are in competition using premium for maximum HP it makes sense.
For commuting or road trips it does not.

I get excellent mileage on road trips between NJ and Florida all on 87 octane

On local short trips while in Florida, not so good

Four fill-ups on the trip down, two local fill-ups while in Florida, and four fill-ups on the return to NJ



My best mileage returning from Florida on a single tank of regular was last September between Lake Worth Florida and St. Mary, Ga. 334 miles and it took 11.255 to fill the tank for a 29.68 MPG.
I never use cruise control as it reduces MPG by 1-2 MPG. Tires are all 35lbs when cold

Telcoman

 

First, the way gas has fluctuated over the last 12yrs, there is 0% chance that you saved a steady and true $0.40-0.50/gal over that whole time. Absolutely impossible to come up with that figure of $4689 unless gas stayed at a VERY steady price, you used the same exact pump, at the same exact station for all 12yrs. Also, that difference in 87 vs 91 is not as extreme in all states. In my state the difference is $0.10/gal/grade which is $3.20 difference per fill up between 87 and 91, so depending on how much you're filling up, I hope $3.20 isn't the difference between you eating or not. If so, you may want to consider another car.

Second, even if that were true, $4689 over 12 years (which would be the most extreme of extremes) that's still only $390.75/yr. That's about 1.5 very nice dinners on the town..if you really want to save money, learn to cook and you can have a very nice dinner for $50.

I love saving money as much as anyone, in fact I have a car that gets 70mpg, that I bought for $2100 just to save money on gas; eventually it will pay for itself AND the G, and then pay ME to drive it. I save over $200/mo driving it.

Make no mistake, I'm not insulting your lust for savings, but trying to "save money" while driving a G37 is pretty counterintuitive. I mean, it's like trying to quench your thirst with salt water.

 

Whatever the case, a lifetime average of almost 26 mpg in a G37 is pretty impressive. My '07 G35S 5-speed auto hovers around 20-21 average, with a peak of maybe 27 mpg at 65 on the highway. That's on 91.

Also, there's no doubt that there is going to be a massive savings by using regular. The difference used to be $.10/grade, but now it's sometimes as much as $.40/grade, so a gallon of 91 is $.80 more than 87, or $16 per 20 gallon tank. I fill up about once a month, so I don't really care, but if you're driving a lot on the highway, why not save some cash?

 

Basically, cuz it's not enough money to worry or make a thread about.