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#21 ·
celicool said:
Interesting observation! I am sure modern engineering can manipulate Octane rating for some intended purpose.

I spent 4 years in the Navy learning all about jet fuels, and that is one of many properties I still remember.
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Not sure that I understand your last comment. Jet Fuel is really very closely related to diesel and has a very low octane rating, but that doesn't matter in a turbine engine.
 
#22 ·
Actually, the functionally equivalent rating for diesel is cetane.
 
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#23 ·
I felt compelled to weigh in here. Octane is a number that is related to a fuel's ability to not detonate. IC engines behave badly when they detonate (pre-combust) inside of a cylinder. Knock sensors are the feedback that the engine processor uses to advance or not the ignition timing. Highest efficiency is obtained for an IC engine at a pre-determined point before the piston reaches top-dead-center. If detonation is detected the timing is retarded a bit until it stops. Under most normal loads, engines will not see detonation, unless of course the transmission isn't doing it's job and fails to downshift or upshifts too soon. Fun fact, the 360 cu in Lycoming engine in the Cessna 172 that I fly has fixed timing (magnetos) and fairly high compression. Aviation fuel is the only fuel that uses tetra-ethyl lead still to get an octane rating of 100 but time is running out on even that use of lead in fuel.
 
#24 · (Edited)
Captorofsin said:
Hello everyone. I've been running 89 octane in my Odyssey since I owned it. I never considered 87 octane.

There's one heck of a price gap between 87 octane 89 octane where I live.

Would it be okay to run 87 octane in a 2010 Honda odyssey?
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Yes, I run 87 octane in my 2012 99% of the time. I've only opted for 89 octane when weather forecast predicted temps below freezing for an extended period of time in hope the higher octane would benefit cold starting etc. It's probably not necessary or may not even add the benefit I proposed, however it gave me more peace of mind nevertheless. In summary 87 octane is just fine and in fact recommended in the owners manual to use 87 octane or higher.
 
#26 ·
devo2u23 said:
Yes, I run 87 octane in my 2012 99% of the time. I've only opted for 89 octane when weather forecast predicted temps below freezing for an extended period of time in hope the higher octane would benefit cold starting etc. It's probably not necessary or may not even add the benefit I proposed, however it gave me more peace of mind nevertheless. In summary 87 octane is just fine and in fact recommended in the owners manual to use 87 octane or higher.
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I don't think higher octane moves you in the direction you want to go on a cold morning. Cold weather starting has been a non-issue since we got rid of carbs. At least in the climates I've lived in, where it doesn't go below -20F. YMMV.
 
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#27 ·
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#28 ·
I've been on several road trips loaded down (and several surf trips loaded down heavy), cross-country, to the Rockies, NE and Canada, since buying my 2015 EX-L. The van seemed a bit sluggish under heavy load but manageable but the game changer was performance on mountainous or hilly highways. Mid-grade was a game changer in performance plus in gas mileage. And in cases where Costco premium is less expensive than mid-grade, I go with the premium. Slightly better gas mileage. Regular gas would be a real strain on me and the van.
 
#29 ·
Captorofsin said:
Hello everyone. I've been running 89 octane in my Odyssey since I owned it. I never considered 87 octane.

There's one heck of a price gap between 87 octane 89 octane where I live.

Would it be okay to run 87 octane in a 2010 Honda odyssey?
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I have a 2010 Honda odyssey it’s got about 97700 on it I owned since it had 24,000 all I’ve run is regular gas in it it averages 22 to 24 on the road has been Muzzled
 
#30 ·
Here is my anecdotal story: I have found that within 100 or so miles of filling up with lower octane gas in my muzzled 2010 EXL, it will throw the "fouled spark plug" code almost every time. If I use premium, it almost never throws the code. Also, over multiple 7000-mile trips, the difference in performance and MPG is verifiable. The engine wants to get up and go when using premium. Feels like a 10 HP increase. It may not be the higher octane--it may be the additives (detergents) that some brands add to premium that keeps the plugs and the chambers cleaner. So I could go back to using 87 octane and add $7 worth of Techron to every 10-15 gallons of gas, but I don't know how much cheaper that would be. And I still might not get the MPG benefit that I'm getting from premium.
 
#32 ·
We’ve been using our odyssey (2010 EX-L) as a spare vehicle and for kid drop off duty, for roughly the last 6 months. I’m in central MS where it’s been 90+ degrees with similar percentages for humidity. Every weekday, the van sees at least 1.5 hours of idling on blacktop parking lots, waiting in line to get the kids. On top of that, I’ve been working on my 92’ Landcruiser which is our main vehicle that we use for our hunting lease… unfortunately for the van, it’s been going back and forth an hour each way for that too. In the past three weekends alone, I’ve towed our 6’x16’ double axle trailer there and back every Saturday. First trip was over 3,000lbs of seed and fertilizer, 2nd was 2 atvs, and last weekend was a kubota crew rtv and 2,000lbs of corn. So our Odyssey has seen some hard use, especially for what it is. On top of that, I’ve been treating it pretty rough, WOT multiple times per day, running low on fuel, basically being about as rough as you can on a vehicle.

All that being said, I only run 87 octane, which I usually buy from a dump of a country store near camp… usually because I’m in a hurry. We’ve run 93 a few times traveling to the mountains in TN, which is usually hauling all sorts of krap inside, 4 people and towing our 5x8 trailer with a golf cart. I couldn’t tell any difference performance wise or in mpg. I’ve never had any issues at all, no CEL, no misfires, no pinging that I could hear, nothing. I do run synthetic oil changed every 5k, it is muzzled and has an aftermarket transmission cooler.

I would guess the folks with the newer vans that have the D.I. engines may see a difference though. My wife drives a 2019 Pilot EX that sees a 100+ mile round trip commute daily, which is about 90% interstate. It’s muzzled and has the 6-speed transmission. I’m picky about the fuel for her car, using only top tier brands. It used to average 24mpg with 87 (for 2 years or so). Last year I decided to run 93 on a whim and on the first tank she averaged 26mpg. From then on I’ve run 93 on it, which still nets around 26-27mpg. I took the Pilot on a 3 hour trip recently and averaged 28mpg. It doesn’t seem to have any more power, but does seem to stay in 6th gear easier, not shifting as much.

I wouldn’t worry much about 87 vs 89 or 93, if our van can handle me beating the hell out of it with 220,000 miles, those who use theirs “normally” should have no issues.
 
#33 ·
We have two 2010 Odysseys, the EXL has 235K miles and the Touring has 95K miles. I've always used 87 in both with no issues. Both are muzzled of course.
 
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#34 ·
Captorofsin said:
Hello everyone. I've been running 89 octane in my Odyssey since I owned it. I never considered 87 octane.
There's one heck of a price gap between 87 octane 89 octane where I live.
Would it be okay to run 87 octane in a 2010 Honda odyssey?
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I hate to say it, but you have been wasting your money getting 89 octane. The Odyssey runs fine on 87. There is no benefit from running 89 as the car will not run different parameters to get more performance. What is more important is that you run a top tier gas, regardless of the octane. That will make a difference in the way your car runs.
 
#35 ·
davedrivesody said:
True no question.

However, higher octane can indirectly increase engine performance in one certain condition: under heavy throttle.

The computer can command more ignition advance. So the engine can extract more of the energy in the fuel.

I use 91 in the mountains. The difference from 87 is noticeable in that the van holds the higher gears longer before downshifting. If the hill isn't too long or too steep, I can sometimes slingshot (i.e. trade speed for throttle) over the top without any downshift at all.

Regardless, I agree with you and the others that anything higher than 87 octane is a waste of money.
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That only happens if your car is designed to do that. The Odyssey does not advance timing to give more performance. It can retard timing to stop pinging. So there is no benefit to the higher octane.
 
#36 ·
09ody20"rims said:
91 no ethanol only and forever
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No ethanol is the way to go, no question about that. Ethanol gas goes bad quickly and can cause lots of problems. But there is no need for 91 octane as the Odyssey is not designed to use it. Where I live the only non-ethanol gas I have seen is 100 octane racing fuel that costs $10/gallon. Even though there are no performance benefits because of the higher octane, I would pay that for my lawn mower and snow blower, which don't use much gas and have periods of time when they are not used, but for my car it is not worth it. Ethanol causes lots of problems for small engines.
 
#37 ·
adr5 said:
The Odyssey does not advance timing to give more performance.
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True, not primarily for performance.

However it does keep ignition timing advanced to just short of causing fuel pre-ignition (knock) to maximize fuel economy and to minimize emissions. (Same for just about all computer-controlled engines of any make.)

Without such a system, the Ody's engine with a compression ratio of 10:1 could never safely burn 87 octane gas.
 
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#39 ·
davedrivesody said:
However it does keep ignition timing advanced to just short of causing fuel pre-ignition (knock) to maximize fuel economy and to minimize emissions. (Same for just about all computer-controlled engines of any make.)

Without such a system, the Ody's engine with a compression ratio of 10:1 could never safely burn 87 octane gas.
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Hear, hear on this.

Whenever I had close to 3,000 lbs. on the draw bar, and climbing into the hills on days where the daytime temps were over 110°F (over 43°C), my Ody felt like it was laboring when the PCM retarded the ignition timing on 87 octane. Just the piezoelectronic sensor (knock sensor) doing its job. I could monitor this on my ScanGauge II.

91 octane allowed me to do the same pull through the hills on the same miserably hot day with a bit more power...less ignition retard due to delay of knock onset. If I kept that boat hooked to the hitch all month, 91 octane got me about 25-30 more miles of total range while pulling. I tracked this religiously when I was using the boat quite a bit.

OF
 
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#40 ·
Today I came across an Engineering Explained video talking about 85 Octane sold in some higher elevation areas:

In it I found another link to an earlier video he did about Premium not always being worth it:

So I guess what I learned is if I'm at higher elevations I'll use Premium or mid-grade, but otherwise use Regular 87 unless possibly if I have a heavy load or am towing.
 
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