Which is the best gas for the Xterra?

[diversetek]

I've been putting in 87 from "76" stations, but I decided to start putting in 89 because one guy told me it would perform better. Since the X doesn't state on the meter "unleaded only", does that mean that we can put 91 as well? Overall, i just want to know what gas is BEST for the X, let me know guys... oh and its 2002 X so if that makes a diff. let me know as well, thanks!

[Canope]

For the SE supercharged, premium is a must. For the XE, like mine, I use 87 until the price per gallon gets a bit lower. That's when I give my X a treat. The manual says minimum of 87. If price was not an issue, I would use higher test all the time. Thomas

[diversetek]

I have an XE V6, so 91 won't hurt it right? Cuz I heard some cars can't handle the 91 or 89 octane gas. I don't care about the price, just want my X to be a happy gal. ehehe

[evergreen]

anything above 87 octane is ok.

[diversetek]

I feel like a super NEWB when i say this, but does 91 really make a big difference in driving? If so, what does it do? perform better, smoother ride, fuel efficient? what? Please teach me, cuz i'm just a kid still ehe

[ChuckH]

Generally, you want to use the lowest octane your truck will run on without pinging. Hopefully you know what pinging is? If your truck is stock and the timing is right you will probably get the best performance from 87 octane unless you are towing or otherwise streesing the engine; then you may want to up it to 89 or more. A few of us with aftermarket engine upgrades have found that hot weather causes pinging, so I run higher octane when it's hot out. Anyway, the answer comes from the sounds under your hood.

As far as the difference in fuel grade goes, it would take more time to explain than I have right now, but basically, higher octane is slower to ignite than lower octane. Generally, higher compression, higher performance engines require it due to the timing and compression. If you use it unnecessarily it could actually reduce your power because it wouldn't ignite as quickly as regular, although I doubt you would ever notice the small difference. Pinging happens when the fuel is igniting before it's suppose to. This causes unburned fuel, wasted fuel, and carbon buildup. BTW, carbon buildup causes an increase in compression and increases your need for higher octane fuel, so avoiding it is always in your best interest. Somewhere in there is a happy medium.

Anywho, the most important thing is to use good quality gas with good additives. Most people (including professionals) will agree that Chevron and Texaco are your best bets for good gas with good detergents. This can vary in different regions, but here in the Pacific Northwest I try very hard to avoid gas from Arco, Union 76, Citgo, and other offbrands. I've found that those companies generally supply gas with excessive amounts of sulphur in it. I try to use Chevron exclusively, but Texaco is my second choice.