What's your Octane?

[Rouse]

I was just glancing over my owners manual and noticed that according to the manual GT owners with the 1.8L (L code engine) are required to use 91 octane or higher. I don't know about you people but owning the Base vibe with the Code 8 engine and using 87 octane or higher at 83 cents a liter at current market value is a serious cash killer. How many of you GT drivers actually use Premium?

[PBFlash]

My GT has never had less than 92 octane in it.

[NovaResource]

The computer in the GT will decrease ignition timing to allow the engine to run on regular however, you will loose some performance and it's not a good idea to drive the car hard that way.

[Triton]

Every tank full has been 92 octane. No less. The couple dollars more it costs to fill the tank is worth it. On top of that, in my area they have I guess what you would call "price wars" where every Tuesday, all three grades of gas sell for the current price of regular unleaded. That makes it really nice and not a hit to the wallet to fill with premium. But as I mentioned before, it might cost me $2 to $3 more per week to fill up at the regular price of premium.

[NovaResource]

quote: tried it, but for the driving the car usually gets it's not worth the money. It gets "regular".Then why did you buy a GT instead of a base?

[millster]

So here's a question. In Ohio, I was putting 93 octane in my Vibe. However, the highest octane available in Montana is 91. I guess the difference in elevation has something to do with the difference in offerings, but what does that mean for the car? Any ideas?

[Triton]

quote:I tried it, but for the driving the car usually gets it's not worth the money. It gets "regular".Remember that this is a "requirement" according to the manual. Sounds like GM is covering themself if something were to go wrong with the motor due to not meeting the minimum octane rating.As far as gas comsumption, I get around 24 to 25 mpg and all I do is city driving. Not too bad.

[millster]

Great, thanks! The next highest option was 89 so I figured I'd stick to the 93 and be safe rather than regret it later. Good to know that 91 will suffice.

[NovaResource]

quote:Hard to get a Vibe here in the Great White North. GT was on the lot and we got it in 5 days.Oh yeah. I forgot about that supply problem North of the border.

[jackospades]

I use 91-93 octane. I'm used to paying for it because of the z28 I had once before. I love this car and mean to have it for a while so I will stick with the good stuff.

[coratz]

sunnoco in canada sells 94 octane as normal premium fuel.

[bellwilliam]

http://caranddriver.com/xp/Caranddriver ... =octaneyou guys want to read this article in Car and Driver, on how octane affects performance. they tested Dodge Ram truck, Honda Accord, turbocharged Saab, Ford Mastang and a BMW M3. The accord was actually faster with 87 than 91 !!! in short:"Our low-tech Ram managed to eke out a few extra dyno ponies on premium fuel, but at the track its performance was virtually identical. The Mustang's knock sensors and EEC-V computer found 2 hp more on the dyno and shaved a more impressive 0.3 second off its quarter-mile time at the track. The Accord took a tiny step backward in power (minus 2.6 percent) and performance (minus 1.5 percent) on premium fuel, a phenomenon for which none of the experts we consulted could offer an explanation except to posit that the results may fall within normal test-to-test variability. This, of course, may also be the case for the gains of similar magnitude realized by the Ram and Mustang.The results were more dramatic with the test cars that require premium fuel. The turbocharged Saab's sophisticated Trionic engine-control system dialed the power back 9.8 percent on regular gas, and performance dropped 10.1 percent at the track. Burning regular in our BMW M3 diminished track performance by 6.6 percent, but neither the BMW nor the Saab suffered any drivability problems while burning regular unleaded fuel. Unfortunately, the M3's sophisticated electronics made it impossible to test the car on the dyno (see caption at top).Our tests confirm that for most cars there is no compelling reason to buy more expensive fuel than the factory recommends, as any performance gain realized will surely be far less than the percentage hike in price. Cheapskates burning regular in cars designed to run on premium fuel can expect to trim performance by about the same percent they save at the pump. If the car is sufficiently new and sophisticated, it may not suffer any ill effects, but all such skinflints should be ready to switch back to premium at the first sign of knock or other drivability woes. And finally, if a car calibrated for regular fuel begins to knock on anything less than premium or midgrade, owners should invest in a tuneup, emissions-control-system repair, or detergent additives to solve, rather than bandage, the root problem. Class dismissed.

[Flip-Side]

quote:If you can get 91, you should get a higher octane if possible...Octane is a direct relation to the compression ratio of the engine...higher the compression, higher the octane has to be since high octane sparks fasterHigher octane is needed in the GT because of the high compression, like Salsa said. Lower octane fuel will tend to "knock" or not ignite at the exact time it is supose to, meaning damage to the engine. It is all summed up here http://www.howstuffworks.com/question90.htm "The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting."

[Cubanpete]

I always use 94 Octane from PetroCanada (at least that is what its labeled) it's expensive and burns quick, however with the current prices I fill up 1/2 tank a week....and I never leave my tank go to zero....I always fill it up halfway..as not to freak me out too much when I have to pay!

[MadBill]

"So here's a question. In Ohio, I was putting 93 octane in my Vibe. However, the highest octane available in Montana is 91. I guess the difference in elevation has something to do with the difference in offerings, but what does that mean for the car? Any ideas? Because of the lower air density, less cylinder pressure is developed at higher altitudes and so less Octane is needed to prevent knock. To save money, less is what the oil companies provide. I have driven cars that were fine in Phoenix, but when filled with the same brand a few hours north in Flagstaff (~7,000 ft.), knocked like crazy as I came back down into Phoenix..._______

[millster]

I thought elevation might have something to do with it, just wasn't sure. Thanks for confirming it. It'll be interesting to see how the Vibe's behavior changes during the trip (if at all). One week and counting. I'll be sure to post a long drive review when I arrive at my destination. It's going to be a long trip having to stick close to a U-Haul though.

[NovaResource]

Yes, higher altitude requires less octane. What runs fine at 7000' may knock at sea level.

[DABEAR95]

I have only run premium 92 or 94 depending on if I fill at Sunoco or Amoco/BP. My Camaro also runs on the same fuel except when I go to the track I add some 107 octane unleaded. My Golf doesn't care about octane, its more concerned with cetane!Jason

[d_m_kolb]

I sale a pretty darn good octane booster if anyone is interested.http://www.twocom.com/high_performance_ ... _Flyer.pdf

[ragingfish]

quote:I sale a pretty darn good octane booster if anyone is interested.Two questions:-- I've heard that you should fill a regular engine with premium once every few months to "clean" it out. Is this true, or an urban legend?-- What's an octane booster do?

[MadBill]

That's right: If an engine doesn't need high octane fuel to prevent knocking, the only possible minor benefit to using it is that premium fuels sometimes have more/better additives, but most regular grade fuels have enough to do the job.An octane booster usually just raises the octane rating, although some may have other additives. (check the label) They are only cost effective if you need higher octane than is available in your area, as typically the cost for enough booster to say raise 87 octane to 91 exceeds the price difference at the pump between regular and premium.

[NovaResource]

Octane boosters are misleading. When an octane booster claims to raise the octane rating by 4 points it means 4-tenths. So 87 octane gas with octane booster is 87.4 octane. Bottom line: waste of money.

[NovaResource]

Yes, additives like Chevron Techron are very good at keeping the fuel system clean.

[yank dini]

I have tried 93 in my new and I do notice the difference in torque. I am able to accerlate faster and smoother.I use 93 every chance I get and I have the base

[MadBill]

I use 93 every chance I get and I have the base[/QUOTE][QUOTE]I have tried 93 in my new and I do notice the difference in torque. I am able to accerlate faster and smoother.High Octane really shouldn't help performance on the base engine, especially enough to be sure of via "(removed) Dyno". Are you certain it's not just the placebo effect? I've found the only way to be sure (absent a G-Analyst or some such)is by using a stopwatch on the same stretch of level ground, do several accelerations each direction, toss out the highest and lowest readings and average the rest; test at the same temperature, fuel and passenger load, etc. For a test like this, accuracy would be improved with a manual transmission by picking a gear that allows you to safely reach redline and run all the tests in that gear, from say 1,000 to 6,000 RPM.

[Flip-Side]

High Octane really shouldn't help performance on the base engine, especially enough to be sure of via "(removed) Dyno". Are you certain it's not just the placebo effect? I have filled my base vibe with Plus or Premium since I bought it, and the first time it tasted Regular unleaded was by my wifes hand. She didn't tell me she put in regular, and I commented right off the bat that the car was running differently. Slightly rougher. She fessed up, and I realized that the premium gas did help. Big difference....no. But I can tell when my wife is jipping my car to help pay for her cigarettes. Caught it evey time shes done it.

[yank dini]

quote:High Octane really shouldn't help performance on the base engine, especially enough to be sure of via "(removed) Dyno". Are you certain it's not just the placebo effect? I've found the only way to be sure (absent a G-Analyst or some such)is by using a stopwatch on the same stretch of level ground, do several accelerations each direction, toss out the highest and lowest readings and average the rest; test at the same temperature, fuel and passenger load, etc. For a test like this, accuracy would be improved with a manual transmission by picking a gear that allows you to safely reach redline and run all the tests in that gear, from say 1,000 to 6,000 RPM.Nope I went back and put 89 grade in the tank. (just couldn't afford the good stuff that day). It immediately went slugglish on take offs and accerlating on the fireway. I never used 93 on my old one and went about 4000 miles before I used it on this one. Trust me there is a difference.

[slinkston]

I use 89 on my Matrix XR.Just for kicks... it is in the middle ground so why not?LOL-Slink

[PBFlash]

My car has never seen anything under 91.

[Triton]

Nothing under 92 here.