Gas Octane question...

[kasar]

Before I fill up another $46.00 worth of gas, does anyone know if there's REALLY a difference between the octane levels? My car suggests 91+ which is what I've been putting in, but I was wondering if I mixed lower octane every once in a while if it would be okay. Not that I'm going to do it, just wondering really.

For the record, I pretty much spend my time puttering around town, occasional highway trips. Thanks, all.

 

[stinkerbelle]

Originally posted by kasar
Before I fill up another $46.00 worth of gas, does anyone know if there's REALLY a difference between the octane levels? My car suggests 91+ which is what I've been putting in, but I was wondering if I mixed lower octane every once in a while if it would be okay. Not that I'm going to do it, just wondering really.

For the record, I pretty much spend my time puttering around town, occasional highway trips. Thanks, all.

I would definetly put in what is reccommended in your cars owners manual.

My FIL told me "ahh - it doesn't matter - put the cheap stuff in!" (FTR - I normally use mid-grade)

last time I ever listen to him...

My SUV (a V6 Pathfinder) knocked and bucked and I could TOTALLY tell the difference with the cheap gas in the performance of my car.

SOME cars WORK BETTER on the cheap stuff (my brothers 2001 Jetta, my mom's 1998 4Runner) but I've found nothing good using a lower octane.

TRY it maybe...just fill up half a tank and try it for a few days...see the performance you get.

 

[Dan Murphy]

The ONLY thing that higher octane does is raise the temperature needed to cause pre-ignition in the air/gas mixture in the cylinder, or simply put, pinging or knocking. The higher the compression, the higher temperature created by the compression in the cylinder, and with a lower octane, the air/gas explosion takes place before the spark plug fires, and you get piston slap, again, knocking. Higher octane raises that temperature that is needed to cause the explosion to occur. You might try a step down, not to 87, but to the mid-grade. If you do not get knock, it is 'probably' okay. Probably, because modern cars, with the onboard computers, can adjust the timing to prevent the knock, but in reality, the car is underperforming, because the timing has been altered by the computer. You hear no knock, but it is running inefficiently, probably lower mileage, in the long run, more costly.

Long story short, probably best to stay with grade recommended.

http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm

http://www.leeric.lsu.edu/bgbb/7/ecep/trans/b/b.htm

http://www.signonsandiego.com/uniontrib/20040327/news_lz1d27fuel.html

 

[Beth76]

Originally posted by Dan Murphy

Long story short, probably best to stay with grade recommended.

Dan, that's the only part of your post that I understood, but thanks for trying anyway.

I've been wondering the same thing. I just traded in my Pontiac Grand Am for an Infiniti SUV. The premium gas (and the larger tank) is killing me. I've been thinking of asking the same question here. I guess I just have to suck it up and use the premium.

 

[MICKEY88]

to avoid possible engine damage, stick with the octane recommended by the manufacturer..

at the very least lower octane usually results in lower gas mileage, cancelling out any savings

 

[momof3disneyholics]

I have a 2001 Cavalier and I have always used the cheap stuff.

Wow, Dan, how to do you know so much?

 

[jel0511]

I'm in the same boat. I drive an Acura MDX, and I put in premium in all the time. I can't wait until I fill it again.... It probably will be over $40!!! YIKES!!!!

 

[Nebsky]

My Mitsubishi Endeavor SUV calls for 91+ octane.
We have tried the cheaper stuff but like Mr Dan said, it knocks and has a funny sound while driving.

We put in the 91 and 93 octanes and it goes away.

We actually get better mileage (23mpg) and more performance with the higher octane gas.

There was a link on USA today about Octane levels and using the lower stuff in performance cars. Ill see if I can find it and edit this to provide the link.

Well, I cant find the link on USAtoday. I know I copied and pasted it to send to my wife so when I get it, Ill repost. It wont have the link in it, but it was from USAToday last week or week before..

 

[Pin Wizard]

Wow, Dan! I'm impressed!

In all my cars I can remember, I've used the high octane. Never had any problems. (If it ain't broken, don't fix it!) Then as gas started creeping up, I occasionally went to mid-grade...then usually mid-grade and just occasionally the good stuff. Now I just use mid-grade. My van seems to do fine, haven't noticed any difference at all. But I'm not dropping to the cheap stuff! I'm afraid of problems then.

 

[shep]

Dan.. ...we stay with the cheap stuff...

 

[caitycaity]

the manufacturer recommends the "cheap stuff" for our car. that's what we've always used and we've never had any problems.

 

[arminnie]

I have a 97 Honda Odyssey. It's only a 4 cylinder (the newer ones are bigger) and only have to use regular. I get pretty good gas mileage for a van.

I was thinking about a new car but I think I will keep this one for awhile as my gas costs are pretty reasonable. I only have 60,000 miles on it. I had less than 25,000 miles on it when it was 5 years old.

 

[Dan Murphy]

http://www.usatoday.com/money/autos/2003-07-30-premiumgas_x.htm

LOL, you guys are funny. Some things you learn and don't forget. I learned that LONG ago, back in the 60's, when I used to be a backyard hotrod junkie. Any octane more than what is needed to prevent knocking is wasted, and higer octane ONLY does that, nothing more, regardless what the oil companies might say. But generally, safest bet is to go with the manufacturer's recommendation.

 

[Nebsky]

I Humbly bow to the master....

I couldnt find it and gave up...

Thanks for the link Dan..

 

[DSNY FN]

Good post I can run regular high octane pump gas in my motorcycle but it is reccomended that I run 106 octane plus. I have a 2000 CBR 600F4 and the motor has been tuned and built by a professional race shop and has lots of race components in the motor. The compression of the motor is now @ 14:1 and it now redlines at over 15 thousand RPM. I get about 118HP at the rear wheel of my 600 on pump gas and if I run race gas or 106 plus octane it is good for another 5 HP. The gas in some cases well with bikes like that will make a difference but in cars it usually doesn't not a great deal of difference between mid and high pump gas but the car will perform a littl less efficient as Dan stated. If you do run a lower grade of fuel then every 3 tanks or so fill it up with premium fuel it will help to clean out the motor a bit I am told.