I know you're not supposed to run your timing advanced without running a higher octane gas. I can follow the concept but am no expert on the physics of the deal. Which makes me ask, is it bad to run high octane gas with factory timing? Is there even an advantage? Any dangers? I started running 89 oct just to see if I could squeeze a few extra miles per gallon on a road trip and I swear it came out a few mpg lower. Just want to make sure I'm not risking detonation from pushing the fuel system the other way.

No, there's no danger, you're just wasting money.

Or, you're taking advantage of the extra detergant packages that are in premium fuel.

As far as I know, the only thing 'bad' that could happen with high octane gas is damage to the o2 sensor. BUT, that is only with gas that is leaded (like some high octane race gas).

-saaby

If you aren't using the anti detonation properties of High Octane gas, then you are wasting money, and loosing performance! Higher Octane gas burns more slowly, with less force. The reason that high octane gas is used in performance vehicles, is that it allows you to run more aggressive timing, or more boost. So, the moral of the story is, use the lowest octane gas that will run with your current settings, and not detonate.

So the whole point of even selling high octane gas is to make more money off of un-educated consumers? And its just a pleasant by-product for the performance crowd that they do sell the stuff cause we all know none of the oil guys do what they do for us. Right??

Not necessarily, many performance and luxury cars require Premium gas because they are either forced induction, or have high compression.

Using higher octane gas is a waste of money if you do not drive your car to the max. You will also see no difference in fuel economy between regular and premium. Nissan recommends that you run Premium gas in most of their vehicles, since most of them use a higher than average compression ration. (any where from 9.5 :1 and up). I have a 2001 Sentra SE (SR20DE) and run 94 octane at all times. I can notice a definite SOP difference in performance. Second I feel a lot safer about preventing detonation since i run the car with timing at 17 degrees and there is not a day that goes by that it is not pushed to the red line. my two cents, if you run your car with advanced timing, and push it hard use yhe highest octane possible. Don't bother with octane additives, they only add a couple of points anyways.
Just my opinion.

Waste of money.

Originally posted by SmoothDaddyFig
Waste of money.
You dont run 93 octane gas with your primera swap, figgy?

Originally posted by sleeping 91ser

You dont run 93 octane gas with your primera swap, figgy?

Yes I do. Only cause Andreas advised to run high octane on the higher compression engine. However when I had the USDM with 17 degree timing I would just run 89.

Speaking of which, my sister put a full tank of 89 octane in my FREAKIN TANK!!!!! and now it runs like ass with 17 degree timing.
:mad: :mad: :mad:

i testify to the contrary of group opinions....

when i ran stock timing....or at least i thought it was stock timing (it ended up actually being 4 degrees instead of 15)..i actually had better gas mileage. By putting in super, i saved 25 cents per fillup. Thus, having nothing to lose, I always put premium fuel in.

however, now that i have advanced timing, premium always goes in.

oddly enough, one of the recent car mags (i forget which one, but either motor trend or road and track) ran a tech article strictly about octane. they ran 89 and 93 octanes on a few different cars to test the hp output from the different fuels. one car of note, the v6 honda accord, put out more hps and torque with the 89 octane fuel. but for most other cars, it was either the same hp output or slightly better with the higher octane fuel.

Thanks for the info and personal experience. I feel a little less "in the dark". With no notice of an improvement as some have stated, I will stick with the 89 oct. until I can get the timing advanced. Maybe I'll throw the extra ten cents per gallon in a jar and call it my performance fund. That way I'll actually get to upgrade something on this car someday.

I buy the highest octance because my timing is advanced. The highest I can buy in my area is 92 and sometimes 93 is available. I don't buy that midgrade ethanol shit because it leaves deposits and can clog your fuel injectors, just like using Heett oo often in the winter, can. As far as cost goes, I figure it costs me a whopping $4 on average a month more than if I bought the low grade stuff, so it's no skin off my nose to buy the best. It's cheap maintenance prevention if you ask me, especially when you are running advanced timing. I won't advance it as high as I could because I can't get higher than 92 octane typically. If higher octance didn't result in higher performance than why do race tracks sell race fuel that has 100+ octane?

Originally posted by Toolapcfan
If higher octance didn't result in higher performance than why do race tracks sell race fuel that has 100+ octane?

For people will high compression or running a lot of boost. All octane does is increase the temperature at which the fuel ignites, to avoid pre-detonation. Its that simple.

After spending quite some time cleaning my EGR system and throttlebody, I used premium just because it has more detergants. Worth it for me, if I don't have to take that stupid highport TB off very often.

I have the JWT ecu now, so I'd need to use it anyway though.

Yeah, I guess my earlier comment wasn't very smart. I wasn't debating that higher octane was good, I just didn't think there were that many cars out there that required it to justify every gas station selling 92 octane. But apparently there are enough cars out there. So if higher octane is better in the right situation, what's the difference between it and "that midgrade ethanol shit." Is 89 oct. gas made differently than 92 oct.?

Not that I'm aware of.

I think it's exactly what it sounds like - not as much octane or detergent as premium.

I don't believe anything more than a 10% ethanol blend is recommended in my owner's manual. Might be different for me though, as I'm in Canada, and there are slight differences in cars sold here.

I don't think most ethanol blended gas has more than 10%, but I just choose not to use it at all, I'll buy the low grade before I'll buy ethanol. If my car was carburated then I wouldn't worry about it, but injectors clog more easily than carb jets do. It seems that in my area all we have is 89, 91 with ethanol and 92. The way I look at it, the only reason we have ehtanol is because the government had to find a use for all this damn corn that farmers keep growing despite the fact that they can't ever get rid of any of it at harvest time. The gov't doesn't want to take a hit due to a bunch of farm foreclosings and banks taking hits for the same reason, so they find ways to get the idiot farmers out of a sling by finding a use for their corn. You can make alcohol out of just about anything, shit they might as well make Everclear out of the corn, and keep it the hell outta my gas.