TinsleyC

How does he figure that? Through lost MPG?

There are a million threads on this and the top is beat to death, but still I question whether or not in a test lab situation, a G37 would go the same or less miles with a tank of 91-93 vs a tank of 87, if driven exactly the same way.

I'm sure many here will say 87 does give fewer MPG, I just haven't tried or measured it.

myk1013

iTrader: (2)

So lets flip the script here...

What if we put in 91 octane fuel into a car that recommends regular fuel?

ANMVQ

iTrader: (13)

I onlt use 93 I would not even think of using 87 in my G,, Heck my mom dosnt even use 87 in here Honda, , With 93 you will see better gas mileage and the intake and valvles will stay cleaner as 93 burns cleaner..

esfoad

My understanding is if the car is designed for regular you are wasting your money putting in higher octane gas. However, if your car requires premium then you will lose horsepower and risk detonation, a serious condition. That said, most, if not all, modern engines can accommodate a tank of regular gas and will retard the spark accordingly without causing any damage. Unfortunately I know of a few people who use regular gas in their Infiniti/Nissan cars for extended periods of time without any obvious damage. Now I use only premium gas myself but each to his own.

1cleanG

iTrader: (53)

Actually no, regular fuel will NOT give you less MPG. Its almost exactly the same. MPG is mostly a result of your driving habits and techiniques, not the fuel you use. I personally tested this when i owned my 35.

I will personally say that I would NEVER use less then premium to "cut costs". If you own an infiniti in the first place, then you probably have the money to pay an extra dollar per fill up for Premium fuel. Questions like this that arise just **** me off...if you can't afford a high end vehicle AND the maintenance of it, then don't get it. Plain and Simple.

Last but not least, Premium DEFINITELY keeps your motor running more smooth, and obviously gives you the extra power you're engine needs(esp when accelerating).

NYCMaxima

If I use 87 (which I never have) in my Maxima which is a VQ35, the engine knocking will get crazy and you will lose power, I have talked to people who have done this, you have the VQ37 Which is higher compression and works much harder, I wouldnt touch anything but premium.

roots4x

Yeah on the fuel filler door it states "premium unleaded only"

HappyG

1. Fewer MPG.

2. Few years back when the gas price was high, a lot of his customer had problem with emission system because they used regular 87. For example, my other friend has a Maxima, he tried to save money by putting in regular 87...but after couple of months his Maxima begin to have emission system problem...he ended up spending a lot more money to fix it. He will never use regular on his Maxima again.

Edit:

QED

Neal376

iTrader: (1)

high octane gas prevents knocking.
knock detectors retard timing to prevent knocking with low grade gas

if your car isnt knocking, then no damage is being done...period

if grandma drives your car on low grade, no knocking is experienced and no damage is done.

if teenager/truck driver drives your car on low grade, and the car is knocking like a popcorn machine, then you maybe subtracting years from your engine. the end result would be damage to the short block, much like what happens to turbo dudes who crank up the boost too much.

JohnEnglish

Wasted money and carbon build up (sometimes). Higher octane fuel is more resistant to detonation so in a low compression engine you might not get a complete burn.

Sometimes people will say "my 20 year old car runs better with premium". In some cases this is true. If they have a lot of carbon build up inside the cylinder the compression ratio will be raised becuase it's now a smaller space. So in some cases putting in premium makes a (small) difference as they now have a (slightly) higher compression engine.

6mtg37s

iTrader: (1)

I tried a little of 87, first off it feels sluggy, and the worst part was how fast it ran out. One would waste more money putting in 87 than 91.

ANMVQ

iTrader: (13)

I see a lot, about knocking, and if you are not knocking them your fine.. How are you guys reading knock( Feel), You almost will never feel KR.. An just cause you think you are not getting it dosent mean your not.. Even if you do I will not cause issues right away but over time if you keep doing it you will boom, Just ask the Mazda guys( Speed3-6) The stock tune on those cars SUX AZZ and see knock all the time, Thats why almost all of us get Cobb and tune it out.. ZOOM ZOOM BOOM, Is there for a reason.. Unless you a monitoring system the only way to "TRY" to not have KR is run 93 OCT..

To the guy with the Maxiam, Same thing happened to my 04, Mom borrowed the car out 87 in it and ran like CRAP for 10 days, I could hear the engine pinging on WOT, Not good had to drive like grandma for 10 days.

carz

there are no benefits, you'll just be spending extra for nothing.

using a lower octane doesnt necessarily lower MPG directly.....but lower octane fuel contains more "dirt" and "sediments" that will negatively effect fuel pumps, lines, and other mechanical parts....which will then effect your MPG

But as you said....if you can afford to drive the car...you should be able to afford the gas.....if not...get a G25 lol

JohnEnglish

Well lower octane gas still has to meet the same quality standards, so it's not "dirtier" it just has a lower octane rating that can cause engine damage over a long period of time. I suppose that it might increase MPG since you'd be accelerating harding trying to compensate for the decrease in power.

As for the G25, it requires premium too.

clutch5

It might be true as a generalization that it makes no difference in most cases, but there are exceptions.

For example the VVT-i 3.0 liter V6 Toyota with engine code 1MZ-FE (if I recall it was in 2000-2003 Toyotas and was 10.5:1 compression) is designed to sense and adjust over the 87-91 octane range, with a slight horsepower and mileage improvement when using 91. I remember this from some Toyota forum years ago, and back when there was only about a 10-15 cent difference between 87 and 91 octane it made more sense to run 91 because it was a cost-neutral result. Might not be true today with a 30-35 cent difference.