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What octane do you use?

  • 85

    Votes: 37 5.1%
  • 87

    Votes: 534 74%
  • 89

    Votes: 81 11%
  • 91

    Votes: 34 4.7%
  • 93

    Votes: 30 4.2%
  • Other

    Votes: 4 1%

What Octane do you use?

32K views 84 replies 59 participants last post by  arteegee  
#1 ·
I know this has been done but let's get some statistics.
 
#6 ·
DoctorJ said:
I know this has been done but let's get some statistics.
I use 87. I've noticed (on the road) that many stations offer 87 and 89 at the same price, however the 89 is ethanol enhanced.

Don
 
#9 ·
I have always found the higher octanes made my vehicles run smoother! 91
 
#10 ·
IMHO, the only cars that really need the higher octane are '60s musclecars. As a side note, I've owned two 1990 Jaguar XJ6's that were labelled saying to use only premium, but following the advice of the Jaguar forum I used to frequent, tried and kept using 87 octane. I still have one of the Jag's now. No detonation/backfiring/hesitation. Always passes smog checks and has plenty of power. I just mention the Jaguar because a lot of people are under the false impression that upscale vehicles would require more expensive gasoline. Not really so.
 
#71 ·
There's some generalizations in this that might lead people to think that running low grade fuel in their cars is okay. Not really so. However, it CAN be done.

Muscle cars did have "high" compression for their day, but new cars all have fairly high compression by 70's and early 80's standards and equal to or is higher than the peak of the muscle car era. Those old V8's did need high octane fuel to prevent pre-igntion. This was partly due to poor engine design and poor fuel delivery (carbs). High octane, in effect, is a great band-aid.

Any late model car will adjust (read: retard) the ignition timing to work with the low octane gas. This will result in loss of power and reduced throttle response. The Jaguar may not be effected much and if memory serves me, don't have very high compression (no more than 10:1). It also might be that Premium is recommended to help better protect from potential pre-igntion problems. Back then (1990) the additives in fuel might have been different for Premium than lower grades of fuel. Hard to say what Jaguar was exactly thinking.

Anyway, speaking from personal experience, if it's summertime and the car calls for Premium, that's what it gets. When it cooler, and the car isn't being driven hard, or on a long trip, one grade lower is used to save $. Highway driving does not put much load on an engine.

I would not say to anyone, that it's okay or safe, or recommended to use low octane fuel. Every car is different, but there is an element of risk.

If one takes the time to read the RL manual, I believe there's a recommendation to use Premium gas when towing 3500lbs or more. Basically this tells me that for optimum performance the engine can and will benefit from more octane, in addition to extra protection provided from higher octane.

I've yet to try this test: read the live data (via a scanner) for Timing Advance with both 87 and 92 octane fuel. Currently the RL has 92 in it......my guess is there will be a noticeable difference.
 
#11 ·
tinsoul said:
IMHO, the only cars that really need the higher octane are '60s musclecars. As a side note, I've owned two 1990 Jaguar XJ6's that were labelled saying to use only premium, but following the advice of the Jaguar forum I used to frequent, tried and kept using 87 octane. I still have one of the Jag's now. No detonation/backfiring/hesitation. Always passes smog checks and has plenty of power. I just mention the Jaguar because a lot of people are under the false impression that upscale vehicles would require more expensive gasoline. Not really so.
Not upscale vehicles, but higher compression engines require higher octane fuel. Most any EFI engine can compensate for a lower octane fuel by retarding the timing which intern lowers the gas mileage and power.
 
#13 ·
tinsoul said:
IMHO, the only cars that really need the higher octane are '60s musclecars. As a side note, I've owned two 1990 Jaguar XJ6's that were labelled saying to use only premium, but following the advice of the Jaguar forum I used to frequent, tried and kept using 87 octane. I still have one of the Jag's now. No detonation/backfiring/hesitation. Always passes smog checks and has plenty of power. I just mention the Jaguar because a lot of people are under the false impression that upscale vehicles would require more expensive gasoline. Not really so.
Depends on what you mean by "need".
As already mentioned, most vehicals today have knock sensor which will compensate for lower octane by retarding timing. But by doing so, cars whose ECU's were programmed for higher octane will lose performance.
 
#14 ·
Since Ethanol mixed gasoline tends to be cheaper here in the midwest, I've been considering using it in my new (soon to be purchased), Ridgeline. But I wanted to buy it from the get go. I have heard that bouncing back and forth from gas with ethanol to gas without ethanol is not good. However if you stick with Ethanol mix you're OK. I can't remember why the heck they said it was an issue. But that's the latest info that stuck in my pea sized brain. Any thoughts on the matter?

Seriously though, I'm not really all that cheap, I put premium in my Passat because that's what the manual says I should. So I'll put the expensive stuff in if I have to. This just doesn't spec premium so I was going to use ethanol in part for the savings and also to support my local farming community.
 
#15 ·
A little ethanol is ok as long as it's not E85. Honda specifically states NOT to use E85 or it will void your warranty. Search.
 
#16 ·
Octane is just the measure of a fuels ability to stay stable under pressure. The common belief that higher octane fuel will give you better fuel economy is wrong... the difference is almost not even measurable, and anyone who says they get better, is making themselves beleive it is worth it. More compression or boost require higher octane, just because the fuel has to stay stable longer during the compression stroke. Use whatever your vehicle says to use. If you use to high an octane, it won't fully burn, and the unburnt fuel will pass through your catalytic converter, plugging it up. The Ridgeline really doesn't need anything more then 87 octane. Sorry for the novel... my bad, and expecially on my first post. :D
 
#17 ·
613Ridge said:
If you use to high an octane, it won't fully burn, and the unburnt fuel will pass through your catalytic converter, plugging it up.
Plug up your cat, where do you get that information from? Higher octane will burn smother and cooler than lower octane fuel. The only way it will not burn completely is if the air to fuel mixture is wrong.
 
#18 ·
DoctorJ said:
Plug up your cat, where do you get that information from? Higher octane will burn smother and cooler than lower octane fuel. The only way it will not burn completely is if the air to fuel mixture is wrong.
Not so sure I buy the cooler part, and the smoother part is also a little questionable. This is my understanding of it, and feel free to point me to corrective information.

The higher octane fuel has the same heat energy as the lower octane fuel, it is just less likely to combust prematurely. If higher octane fuels really burned cooler but allowed for the same or better performance it would make sense to use them in all cars because it would lower the amount of heat pollution caused by vehicle. The reality is that about the same amount of heat is produced regardless of the fuel used. Smoother is more of how it effects the engine. It has less of a propensity for premature combustion and therefore causes engines not to knock, this would cause the engine to run more smoothly but doesn't really impact the burning of the fuel itself.

As to the myth though, you are spot on, the reasoning behind it that I have seen, and there are probably many theories, is that because it burns slower there is the potential with the lower compression vehicles to have started the exhaust stroke before the high octane fuel has completely burned because the fuel was never compressed enough to cause the immediate explosion required to burn off all the fuel quickly.

But if you can point me to somewhere that talks to the cooler and smoother aspect I would be curious.
 
#20 ·
5S Dude said:
I've read elsewhere on the net that if you pull a large loaded trailer up mountain roads, that a higher octane can be of some benefit. Is this true?
We found that to be true on our latest trip. Our first trip towing with regular (86?) we only got about 12 mpg. This trip we used premium (91?) and we got about 15 mpg. No noticeable difference in performance but the mileage was better.
 
#21 ·
The owner's manual states that 87 octane is the ticket except if you are towing, then you need a higher octane rating. The way to tell is if you get any pinging. If you do, get thee to a high octane pump;) . If you have a full tank of 87 and start pinging you can use some octane booster to finish the tank. If you aren't towing and aren't pinging you are wasting money if you use higher octane.

Octane boosters are used to reducing the "ignitability" of the fuel under high compression situations. They also help if the engine is running hot (like when towing). It does NOT increase the "power" of the fuel. It just keeps it from pre-igniting (pinging). You can void your warranty by driving with a continuing pinging problem.
 
#23 ·
The way to tell is if you get any pinging. If you do, get thee to a high octane pump;) . If you have a full tank of 87 and start pinging you can use some octane booster to finish the tank. If you aren't towing and aren't pinging you are wasting money if you use higher octane.
I doubt that you would ever get any pinging in the RL. The anti-knock sensors in the engine would compensate by changing the timing and would result in a loss of power, but no pinging.
 
#26 ·
Zemog said:
Hey, the manual says 87 octane so thats what I use. Besides, it's cheaper!
Hi Monte! JMHO, but feeling the engine run smoother (if that's possible!) and more responsive, is worth the extra two dollars more for a twenty gallon fill-up. I'm still tracking my MPG with 89. It seems to have improved, at least on highway. We'll see:) Besides, the manual calls for a minimum of 87, and recommends higher octane for towing...I believe.