what octane should I really be running?

[GuSpeed]

I have a 92 Nissan 240sx with 130k Injen intake and some catback exhaust. I have been running 87. Is this bad for the car? Thanks.

[Project S13]

I believe in the owners manual it says to run premium grade octane, but if you are unable to for some reason 87 is the lowest acceptable grade. I used 89 when i first got my car but since then (150K+) all the injectors died. Now that they're replaced I use 93 most of the time, I love my car. More than I love not being broke haha.

Anyway, I guess technically the higher you run the better it will be for your car (of 87 thru 93 at least) it's up to you. There's my .02 anyway.

[yeap]

I run 91

[574-240sx]

I have run premium in all my cars I have ever owned other than my civic I owned in high school. I run 93 octane in my maxima and sometimes 100 octane in the 240.

[Bruno240]

my manual never said it needed premium. Now my 300zx says it does, so i do. putting premium into the 240sx is kind of a waste of money when it doesnt need it unless you have some horrible carbon deposits and your engine is knocking with anything else. What you do is you run the lowest octane without getting pinging or knock and your not wasting money on unnessary octane.

[574-240sx]

I fill up with 100 octane if its a hot track day just for extra insurance.

[azncorruptedo17]

i run 89 on daily =]

[Juujai]

i just dont really drive in hotter days just because theres a higher chance stuff can break. radiator... etc haha

u guys arelucky california has crappy 91 octane that feels like crap

[Turb0wned]

93 all the time but thats because i dont wanna run anything lower on the sr....

[Z Style]

There is no need to run a higher octane than regular unless if your engine is knocking or pulling timing and robbing you of power. So you may want to up the octane and see what it does, if you can't feel a difference than it is un-needed.

[9095240SXDUCK]

I run 93, on all 4 cars.

My Dad 99 Accord V6 And my Step mom New 04 Camry runs 93 also!

[Tsukai240]

i run half a tank of 89 then top it off with 93. about 25 bucks!

[sanioll]

i run half a tank of 89 then top it off with 93. about 25 bucks!

LOL.. that is really good.

i simply run 93 octane level, thats what it says on the side cover, so thats what i run.

[Tsukai240]

LOL.. that is really good.

i simply run 93 octane level, thats what it says on the side cover, so thats what i run.

well the owners manual for my 91 s13 says to run 91 so one part 89+one part 93 =91

[frapjap]

91-93 lately. I was prepped for Nitrous, so I swapped the stock plugs for a step colder spark plugs and when I don't run the good stuff, she shudders all over the place. But idles awesome and runs even better on the premium.

[BadMojo]

I run 91 octane if I can find it, per the manual. As was mentioned before, no point in running higher than recommended unless you've got a forced induction set-up, very aggressive timing, or a high compression NA setup.It's really just a waste of money to run 93 octane on a mostly stock KA engine in good working order.

[bcar240]

I am not sure this is true, but I heard from somewhere on here that it is best to either run all high grade gas, or mix high and low. Because the mid-grade is usually the same as the low grade but with additives. If anyone knows please inform me, cause I want the truth on this.

[masticatingcow]

I think that the additives you speak of are more built around the brand of gas you buy, not the octane rating. All gas companies get their gas from the same sources, and add their own stuff later.

People talk about 91 octane like its battery acid, and then talk about spiking their tank with toulene. If you run a pretty stock 240sx, you don't NEED anything better. It's not like the KA is inherently a tightly-wound performance engine.

GuSpeed, you say you have an Injen intake and some catback? Okay, well, here's a couple other questions...

Do you wait until redline before you shift? In that case, higher octane is good.

Do you notice pinging or knocking, or does your CEL come on regularly? In that case, along with a few other changes you need to make, switch to higher octane.

If your car runs fine on 87, there's really no reason to change it. I ran 87 for the first year and a half that I owned my car, and I run an Injen intake and Hotshot headers. You should have no problem.

Note: I run 91 now because the motor just clicked over 224000 miles. I probably didn't NEED to, but I drive less often now, and can afford the extra 20 cents/gallon.

[Twinchy]

iam running 89 all the time

[dfw240_EE]

Little trick my dad mentioned to me, run premium for a tank or two before your emissions test. He thinks it helps abit, but I haven't put it to the test.

[gepeto]

Stock KA, 245 000km, always ran on 87 (well at least for 180 000km) - not a single problem ever.

[ace135cc]

i run on 87, and occasionally ill put 89 or 93 if the price is right.

[mmatl16]

when i had my ka i would run 91 all the time. i dont know maybe it was just my imagination but it felt like it ran better and it made me feel better not to be cheap on my car. i think its worth the extra 10 cents.

on my rb I run 91. but i went to the local airport once and pumped gas and it felt wonderful. i couldnt even tell u what octane that was. something like 107 im sure. the gas was like a pink color. lol. but at 3.50 a gallon it was a one time thing.

[GuSpeed]

Thanks. I have 92 octane where I live. I notice running 87 it kind of bogs going up hills. So maybe I will run 92 octane.

[aleph1]

Depends on your altitude as well thought I believe. If you are in a higher altitude, then the there is less air, henceforth you dont need as much octane. (only applies to NA engines) Here in Denver the norm is 85,87,91...I ran 91 for a bit after moving from San Diego, but the car was really boggy and sputtered a lot, switched to 87...problem solved. =)

[Juujai]

i heard higher octane = better mileage also. the lower grade gases arent as pure so it burns weirder. im not too sure i hear that from people sometimes.

[ArticDragon192]

I run 87 on my stock KA. It runs just fine.

[Bruno240]

i heard higher octane = better mileage also. the lower grade gases arent as pure so it burns weirder. im not too sure i hear that from people sometimes.

octane is all chemistry. gasoline is made of hyrdrocarbons, and some hyrdocarbons are stright with all single bonds and burn a lot faster than the hydrocarbons with kinks from a double bond. In our lovly internal combustion engine the hyrdocarbons with all single bonds and straight burns too fast for it to used to its fullest and you get preignition. but the hyrdocardbon with kinks from double bonds burns slower and doesnt pre-iginite and is used to its full potential. SO, the octane (and octane is because there are 8 carbons on gasoline we use and 8=OCT) is the rating of how many double bonded hydrocarbons to how many sing bonded hydrocarbons. the higher the octane the more double bonded the better gas it is.

so in conclusion

single bonded hyrdrocarbons=baddouble bonded hydrocarbons=good

more double bonded hydrocarbons the better and high octane.

[elbles]

That sounds about right, from what little I remember of my various chemistry classes that I am ever so thankful for being over with. :-)

However, there is more "energy" present in a given unit of gasoline as the octane DECREASES. As it relates to an IC-engine, a higher octane will simply prevent premature detonation/knocking. Unless your car specifically requires it, or you are hearing knocking related to premature detonation (i.e. not rod knock), you are wasting your money on higher-octane fuel. FWIW, my "empirical research" (not extremely formal, just average MPG calculations . . . filled the tank up, divided miles traveled by the number of gallons it took) showed a 2-3 MPG increase when I switched from 89 to 87 octane on my rebuilt KA24E. I would imagine that the DE is no different in that respect, but treat those VG30DE and VG30DETT's right. :-)

[skydragoness]

I ran 89 octane when i first purchased my car, for the first 4 months or so. Then i switched to 93, it just felt and sounded like it ran better on it. I have been running 93 octane since then (02') and since my iginition timing has been advanced to about 22 degrees, 93 octane is mandatory. I particulary like the Shell V-Power 93 octane, i've noticed the car is peppier on it. Cost does not bother me, i don't drive far and i fill up to about 1/2 a tank usually (i don't wait for it to suck the bottom of the tank either), honestly if you can't afford to fill up the 240's small tank with 89 or 93, then you should've got a Corolla. It's not the gas that hurts my wallet its the expensive Nissan parts