Gas

[gshock888]

Kinda dumb question,

Am I really wasting money with high octane gas with my '02 SE (no S/C)? My friends told me I should be fine with low octane 87 gasoline.

It's just I'm not comfy with cheap gas. But at the rate the X drains it dry, I'm starting to think about it.

[StageOneGalant]

The higher the Octane the faster u're gas burns.. lower octane slower the gas will burn.. but. it's best to put higher Octane for the newer model car, jus cuz, while testing those newer engines' Car companies usually set up /and test the car on high octane fuel/gas.

[wqbang]

Actually, the above is wrong. Higher octane prevents detonation can be common in high compression engines. Octane actually causes the fuel to burn "slower" for lack of a better term by reducing the fuels tendency to ignite early due to high temperature and compression. The reason car manufactures are recomending higher octane ratings is because modern engines are higher compression.

The SC in your Xterra is increasing the compression in the cylinders and in order to prevent detonation, it is recomended that you use higher octane. If you wish to, try out a tank or two at 87. If you are not experiencing any pinging, it may work for you.

Here is more info for you:

What does octane mean? - Howstuffworks.com
http://www.howstuffworks.com/question90.htm

[OffroadX]

You probably won't have any pinging with regular, but that's because the knock sensor will detect it and retard the timing to prevent it. You'll probably end up with less power than the non-SC models in the process.

Don't dick around, cough the extra $2/tank and trust that Nissan's highly-trained engineers knew what they were doing when they designed the system. Oh, and read what your owner's manual says about fuel recommendation and using regular in a pinch...

Brent

[cvanwie]

I'd have to agree. My Xterra SE 2000 has been running on 87 oct. even through the mountains, cross country drives, etc. About once a month I load it up with 91oct (california now) and it seems to make a slight difference.

Really depends on the way your truck is feeling/sounded. Let your ear and eyes make the decission.

[SarnX]

I have a 2002 SE/SC and I am also a chemical engineer. The description of Octane located in the how things work section in the post above is very accurate as well as the comments that the SC engine is designed for a higher compression ratio and as a result does require a higher octane to ensure that you do not have pre-mature detonation. I personally would not want to chance using the lower octane fuels in this engine.

My 2 cents,

SarnX.

[Xsupercharged]

Since you mentioned you DON"T have the supercharged model, it is not recomended using higher octane than specified in your manual. I know a lot of people who have tried higher octane in a normally aspirated-non turbo or non-supercharged engine and it made NO noticeable difference in performance on the street or track if your car is not tuned up for it.
Personally, I have the supercharged X model now and previously had a Big 16G turbo 99' GSX Eclipse than ran 13.2's daily driven prior and I know if I don't use high octane, my car ran like a snail in salt in comparison, and at the track if I didn't tune my AFC accordingly and ran 100 octane race gas my car would stumble over itself trying to get out of it's own way. So to rap it up only use what you car needs, and it only needs 89 otane. Save your money for other mods.

Hope this helps.. :ylsuper

[OffroadX]

Well duh, I totally mis-read the original post. Since it's NOT an SC model, then yeah, you're wasting your $ on premium. Use regular, keep it properly tuned, and you should be set.

I'm just so used to SC owners asking if they can get away with regular that I just read it that way.

D'oh!
Brent

[Schludwiller]

I was reading this post and wondering when someone was going to notice the no s/c thing.

Your engine is designed to run on the octane gas recommended in your owners manual. Going with higher octane on an un-modified engine is just wasting money.

Now go buy some new mods for your truck with all that money you save.

[gshock888]

Thanks everybody. Yeah when are you guys gonna take notice that non-S/C users actually DO come into these forums? lol :silly2:

I run my X in NYC and it dries the tank in hours! I filled it up yesterday and two trips to Long Island (~50mile) yesterday and today and its over half gone! This is crazy! So thanks everyone for your reply, I will make sure I go with cheaper octane gas for now on!

The first cosmetics/external mods i definitely need are the grille guard, tailight guards, wind deflector and front deflectors, before I even start touching the engine.

thx again

peace :sun:

[OffroadX]

You might want to review the "Brush guards...... BAD!" post in the School of Hard Rocks section before you go and buy a brush guard. This describes an incident on the trail, but it's equally applicable to urban environments.

Brent

[tlcafj60]

If you switched to an aftermarket ignition like MSD, you may be able to use 87. You would get a hotter and longer burn than you would with the stock ignition which in comparison to MSD would be 'cooler' and shorter. This could compensate for not using higher octane and prevent knocking.

Although it will be said as well that by using an MSD and 93 would still be better....

My $0.02

[tlcafj60]

I just re-read the original post too. Oh well.

Just use the 87. If it pings, check the timing and then maybe your valve lash. I know that a valve that is out of clearance can sould like a ping at acceleration and at speed.

[wqbang]

Yep didn't read it either. I hope my post helped everyone anyway!

HowStuffworks.com has got to be one of the best websites on the net and is a personal favorite.

[perrya4]

I just got my new 2002 SE V6 S/C a few weeks ago, and having switched over from a Honda, the poor gas mileage is killing me!

What have you all seen as an average total mileage from a full tank of gas? Am I just going to have to succomb to the fact that the mileage in the Xterra sucks, or is there anything I can do to make it better? Help!