Premium gas or regular

[LGM]

My girlfriend has a 2006 Pathfinder LE and on the gas door, it says Use Premium gas for maximum performance (or something to that effect). What would be the benefits in using Premium over regular or even mid-grade fuel? Is it worth the extra cost over the life of the vehicle? (mind you,we're paying under $1.00 for premium gas now, but for how long?)

Thx!

[PiDGE]

I've got an 05 frontier, same motor vq40 and I'v been running low test since new with no problems.

[Bow_Tied]

The higher octanr fuel allows the computer to take advantage of a more aggressive engine timing for more power, better fuel economy. Engines with variable valve timing I think would be able to run a tighter sequence too. I run mid grade in my 02 without issue, lots use 87.

[Scotto]

There's a lot of info out there on what a higher Octane count does, so I won't bore you too much (and you probably already know) but in a truck a higher octane really isn't going to do a lot.

The octane controls when the burn begins - a higher octane will allow the fuel to pressurize to a greater degree, allowing for burn closer to the top of the stroke. It's more effiicient, as the burn is more controlled at the begining of the power stroke, and makes for a big difference on vehicles set up for that kind of burn. Like VW VR6s. These kind of engines, being somewhat intolerant of an early burn, begin to knock.

But in a truck, it don't matter. Your pathy is fine with the normal, Joe-blow stuff.


Scott

[Bow_Tied]

http://en.wikipedia.org/wiki/Octane_rating" onclick="window.open(this.href);return false;

[LGM]

Thanks for the information. I know google is my friend, but google lacks personality and I wanted the opinion of fellow Nissan truck owners. I appreciate the help. I was also concerned that there may be some warranty issues from Nissan if we were not using the recommended gas grade, but in hindsight, I guess that sounds of silly.

[Nd4SpdSe]

There's a nice blurb in this months R&T.

Pressured by Compression

I drive a 2004 Honda Accord V-6 that uses regular fuel. My Accord runs flawlessly and I am very happy with it. My pet peeve is that upscale sedans made by Acura, Infiniti, Lexus, Audi and Volvo, among others, require premium fuel only. This strikes me as a waste of money. The performance of my Accord does not take a back seat to any of these upscale sedans, so why do automakers require the use of this expensive premium fuel?

John Mercer
Easley, South Carolina

Efficiency of internal combustion engines depends largely on raising the pressure inside the combustion chamber during the power stroke. A good way of doing this is to raise the compression ratio, or how hard the engine squeezes the air/fuel charge before burning it.

The trick is, higher-octane gasoline is needed with high compression ratios to retain control of the combustion event. So, more efficient engines have higher combustion pressures and require higher-octane fuels. Such high-output engines tend to be found in upmarket cars, as you cite.

Once the engineers tune an engine to run on premium fuel, they can harness the extra efficiency as either extra power or increased fuel mileage. In reality, once you correct the calculations for weight and power, you'll find many of those prima donna sedans best your Accord in performance, either on the road or at the pump. Furthermore, with the help of knock sensors, the same cars can run on lower-octane regular gasoline, albeit with reduction in power and mileage.