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Would you run 87 octane if was FREE???

8339 Views 28 Replies 16 Participants Last post by  skirmich
My wife has gained the "perk" of free gas at her job. Unfortunately, it is only 87 octane.
Our 2015 MDX has always had top tier brands of 93 octane, but I hate to pass up FREE!
Around here we have 87/89/93 octane choices.
She usually burns about one tank per week. It would save us about $50 weekly.
Is there an octane booster that she can add at fill up that would allow us to take advantage of this new opportunity?
Your opinions are appreciated.
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Unfortunately car computer is optimized for higher octane. Don't think there are any real octane boosters out there that would do what you need. I'd be either looking for a way receive the perk and pay for the upgraded gas or figuring out how to fill up the car with low octane and then pump it out into another vehicle.

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There are octane boosters, but they would dilute your savings. Engine management computer is perfectly capable of adjusting to lower octane fuel. There may be a slight decrease in performance and responsiveness. I would use the free stuff, and reconsider if you notice pinging or drivability problems.

BTW, I'm pretty sure 89 octane is blended at the pump from 87 octane and 93 octane. Hint.
What about alternating - one free and next high octane, or at say a 1/2 tank top off with high octane every other time.
No, I can tell a difference on top end power on both of my MDX's. Sluggish comes to mind.
if you put 87 other things might go wrong or break easier or wont' last long term.
id alternate between the low end and high end.

whatever rocks your boat.
I would fill half tank with 93 and top off with the 87.
I been filling up with top tier 87 octane since I bought it new 1 1/2 ago.

I haven't put a single tank of 91 octane ever. The manual recommends it, and it's not required. It will not void your warranty.

This fuel thing is waaaay overrated.

Yes you'll get better performance. But who races around town and worries about how the car performs. I'm not making a living racing this thing on a track.

I've never had any knocking or other issues. I have 34,000 miles.

I average 22 mpg around town. I've seen as high as 29 mpg on a long road trip at top speeds of 65 mph.

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^ Really has nothing to do with racing.. In general you are reducing the engine lifespan by running 87 on a High Compression Honda engine. Read this for more info:
I'll take my chances.

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Are you a mechanical engineer for the automotive industry?

A chemical engineer for the petroleum industry?

How do you know all of this?

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I am a Mechanical Engineer..
That thread was entirely dumbed down to more simple understandable words, It wasn´t made to be a debate thread...
The whole engineering lingo makes no sense to most people who read this stuff on the forums, Anyone that knows what "Fuel-Ratio" and "Stoichiometric" is wont even use Regular on a High Compression engine.
Hey but you can run what-ever you want, Its your money and your engine...
It seems a little odd they'd add this perk but for only regular gas and not premium but then, the perk is an unusual one to begin with. Can she fill up anywhere or is this from some captive pump at her job site? If it's anywhere, it might be worth it for her to contact HR and ask some more about this benefit indicating her vehicle recommends the use of premium and whether they can consider allowing them to use premium even if it's only paid at 90% or something. Sometimes companies come up with things like this but it's decided by people who have no clue of such things as premium fuel being recommended for particular vehicles. A little education and requests might help them expand this.

The owner's manual states it's okay to run 87 octane albeit at a lower performance level. It does not state that damage will occur or not to ever run it. There have been long threads here debating the use of lower vs higher octane with people having their own unsubstantiated opinions, but I stick with what the manual recommends - premium, but I'd feel comfortable that I could put 87 in it if I felt like it and didn't care about performance (but I 'do' care about performance).

You'd still have the option to use 87 normally and then put in premium when you know you'll be travelling in the mountains, etc.

$50/week is $215/month which is a lot of money to discount without having a legitimate manufacturer confirmed reason not to do it or a desire for the most performance possible on a daily basis.

Another relevant point - depending on your mileage, you may have a lot more warranty left on the vehicle and depending on whether you plan to keep this for the very long term or just a couple more years may influence your decision if you have any concerns about damage to the engine, even though the owner's manual doesn't indicate that'll happen (assuming you don't notice any knocking, etc.).
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I'm well aware of what stoichiometry means, and I'm also aware that my 2016 Pilot runs fine on "recommended" 87 octane with exactly the same crazy high compression ratio as our 2014 MDX. Maybe it's PFM, or maybe the magic is direct injection and the advanced engine controls that go along with it.

On the other hand, our 1st-gen MDXs do NOT like it if we cheap out on fuel, especially if they are carrying a load or towing. Technology marches on.
I'm a stickler for using premium fuel when recommended/required but no way would I pass up free regular grade fuel. My wife is the primary MDX driver and the way she drives she would never know the difference in performance and I'm 100% sure there would be zero negative effects on the engine. Usually the argument on 'premium recommended' cars is that you'll see a reduction in mpg when using regular grade but when it's a free resource it becomes an invalid argument. I guess I'd want to be sure it's a top tier fuel and not some stripped down generic fuel.
I put 87 regular all the time on my 2001 and it's 266K miles now. Replaced trans at 222K. Engine still runs great. Maybe it's purely luck.
the higher octane protects against detonation better, You could probably get away with it if you live in Denver but I would not do it at sea level. You might find a cheap octane booster that you could use - of course you could buy 3 ea 5 gallon Jerry cans, fill them with 15 gallons and sell to the neighbor at a reduced price then use that money to buy premium. If you have more than one car and it takes regular then have her drive it to work instead.
The alleged protective effect of high altitude dates back to carbureted engines, and I seem to recall reading that it is inapplicable to modern fuel injected engines, if it ever had any merit at all ( which is questionable ). But when bad science enables profit it tends to persist long after it has been debunked.
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