Reg vs Premium fuel?

[Millerman]

Hey there

In my Xterra Nissan recommended premium fuel but when I tried using regular the truck would **** and moan about it. I was told that was because the truck was equipped with a supercharger and the supercharger needed the higher test. The LR3 also recommends premium fuel and that is what I've been feeding it since I got it. So my question is, does filling with regular have any noticable effect.

Cheers
Dan

 

[e24kgold]

I have not used anything but 93. I dont know why you would try reg. or mid-grade. I'm guessing cost is an issue . My feeling is, if you buy a car that recommends the use of a certain fuel, why not just use it. The LR3 new is a $48,000+ car. When spending that kind of money, the fuel cost shouldn't be an issue. Just use 93 or 91, your car will thank you in the long term

 

[huelsmma]

I have not used anything but 93. I dont know why you would try reg. or mid-grade. I'm guessing cost is an issue . My feeling is, if you buy a car that recommends the use of a certain fuel, why not just use it. The LR3 new is a $48,000+ car. When spending that kind of money, the fuel cost shouldn't be an issue. Just use 93 or 91, your car will thank you in the long term

Agree...it's only a $5 difference between 93 or 87 octane

 

[roverman]

Thank God it's another fuel thread....

 

[schafari]

The engine is tuned for a minimum octane. If you run regular. . .yes, the truck will run. . .it will adjust and ****** timing, not put out as much power, and likely end up using more fuel as you will still try to get the same old performance. (You will push the go pedal longer and harder to get the same performance you are used to. . .

Just run premium

 

[Team Jeff]

I've had issues running 87 & 91 (AZ)

Poor economy with 91 & engine pulls timing on 87. So I've been using 89 with good results.

As you may or may not know the octane rating relates to the combustibility of the fuel. It's much more complex than that & I'm no expert on fuels! Bottom line is - run the car on the minimum possible octane fuel that will support smooth operation. Anything more is a waste, albeit very minor.

 

[tommithy]

As you may or may not know the octane rating relates to the combustibility of the fuel. 91 octane gasoline has less energy per unit than 87 for example.

You are partially correct here.

Octane rating measures the ability of the fuel to resist auto ignition and burn in a controlled manner. It is not a measurement of the fuels energy content or Heating Value.

Pound for pound a 91 octane fuel will create the same energy content as an 87 octane fuel only it is more difficult for the 91 octane to be ignited (less chance of auto-ignition). However when the gas companies started using Ethanol to increase octane rating this went out the window as Ethanol actually lowers the energy content of the fuel mix because the energy content of Ethanol is lower then gasoline.


I personally do not run a lower octane fuel then recommended as it tends to cause the vehicles engine management system to ****** the timing to avoid auto-ignition under load. It may work great if all you do is cruise flat roads at a steady speed but if you start putting the engine under load it will succumb to auto-ignition and then computer will have to ****** the timing thus cutting the power output of the engine.

 

[Millerman]

Thanks all. I'm used to running the good juice so not a cost issue but like to save money where I can not at the expense of performance though.

 

[Team Jeff]

Interesting tommithy, thanks for the clarification!

Now I'm curious why I seem get better mileage using 89 Vs 91? Maybe it's neuro induced

 

[Disco Mike]

I can't believe that when the manufacturor of a vehicle says use Premium only, someone has to ask any way.