ColoRDX

I know 91 octane is only recommended and not required per Acura. I've burnt at least a half a dozen tanks (each) of 87 and 91 octane in my 2021 RDX. I cannot honestly say I get better gas mileage or acceleration performance with the higher octane. Determining a true mpg difference by the average driver would be quite difficult to obtain. One would have to duplicate identical routes, speeds, brake applications, engine idle time, wind, weight load carried, etc., etc, for each grade of octane used.
When I've gone from 87 to 91 octane (4.6% higher) I want to think I'm feeling improved acceleration/performance but, I can't honestly say so. Same goes the opposite from 91 to 87.
Has anybody out there made multiple 1/4 mile clocked runs using both 87 and 91 octane to experience what actual performance difference there is?
Personal opinions and gut feel mean very little. Does anybody have any real facts they can share?

comanche250

I'm like you. I've done the same thing and "gut feel" cant feel a difference. Same with gas mileage. So beats me. Not worth trying to do any research above that...to me.

russianDude

Depends also on price difference, Costco has always been 10-20 cent difference. Others charge as high as 80 cents’more

Pair of TLs

https://fueleconomy.gov/feg/octane.shtml

Baldeagle

As a surrogate, Car and Driver did a few tests on the 2.0T Accord. It’s the same engine and 10A (minus the SH-AWD) as in the RDX. On 87-octane, that engine, like the RDX's engine, produces about 252 hp and on 93-octane it produces 272hp. On regular fuel, the Accord traps at 99 mph and on premium fuel it traps at 101-102 mph. Given that the RDX traps around 94 mph on premium (272hp), it might be 92-93 mph on regular (252hp). Hard to feel that difference on the road.

ColoRDX

Thanks for the excellent info. If Car and Driver numbers hold true, burning 91 octane versus 87 octane for a .01% - .03% performance increase is really rather foolish unless a substantial mpg increase can be proven.

JB in AZ

I drove my 19 Advance FWD over 30,000 and never used anything other than 87 octane in the fuel tank. Never felt the lack of acceleration.

ColoRDX

Yep....about 60 cents more per gal for premium here in the Denver metro area.
After reading Baldeagle's post, running 91 octane in your RDX is basically a make you feel good thing.

ColoRDX

Just curious......did you ever try 91 octane to see if you could better your MPG?

EFR

at these prices, regular it s, and have noticed zero issues.

JB in AZ

No, I never did, sorry. It is likely a fool's test, as it would be very hard to drive the exact same way, etc on a test tank.

oblio98

Same with me, The only time I'd use premium is if that gas station only sold regular and premium, no middle grade (like Costco). And those times I noticed absolutely no difference in the car's performance - in 65,000 miles (2019 A-Spec)

I have never used regular tho

JB in AZ

Costcos here only sell two grades, 87 and 9x(?) "premium" I don't even know the octane....LOL

russianDude

Did anyone try comparing mpg in sport vs comfort mode? Seems to be the same for me …

Baldeagle

The difference in fuel economy between 93-octane and 87-octane might be .5-1 mpg. But if you use 87-octane to reduce fuel costs, the odds are high you are also driving easier to improve fuel economy. If driving easier nets you an extra 2-8 mpg, the .5-1 mpg lost to 87-octane means nothing.

And if 252 hp implies a 0-60 time of 6.8s verses 6.5s on 93-octane, is that a big deal? And in daily driving, does it really matter if you need 38% throttle (87-octane) versus 37% throttle (93-octane) to keep up with traffic? Or to produce the 25 hp required to maintain 75 mph on the highway, does it matter if you need 8% throttle versus 7% throttle? Who could possibly feel or notice that?

russianDude

I just paid 10 cents more for 93 vs 87 at costco. How does 10 cent factor in, $1.40-1.50 difference per tank

JB in AZ

Today, 3/6/2022 at the Costco here, 87 is $3.89, 93 is $4.33. It is all relative.

russianDude

yep, just saying that price difference will influence the decision to get 87 or 93.

rbbcpa

This comment is not directed at OP but to comments in general. The use of 91 octane is not just for performance only. Most 91 octane is blended with a proprietary detergent additive to help keep the engine clean and to reduce emissions. There are too many variables that affect performance; however, the benefits of top tier detergent gasolines cannot be ignored. This article supporting this was published 4 days ago. Click here.

JB in AZ

Correction, perhaps Costco here sells 87 and 91 octane, NOT 93. I only recognize it as Regular and Premium!
AKA: LP and HP (Lower Price and Higher Price) LOL

JB in AZ

Of course, "Top Tier" and "91 octane" are different things.

tecwerks

The price difference now a days between the different grades is more like 30-40 cents per gallon. 10 cent spread disappeared years ago, can’t even remember when.

JustMe...

In Illinois, it used to be 10 cents difference between each of the 3 grades. Say 87 was $3.00, 93 would be $3.20. Over the past 10 or so years, the difference has been between 30 to 40 cents between grades, as you noted. I have no idea what happened, but it stopped me from putting 93 in a vehicle that recommended 87. I do put 93 in my '21 Ranger, but only because I only drive it a few times a year. Probably a waste, but I'm thinking/hoping it has better lasting qualities than regular 87 octane. I just filled it up yesterday for the first time since last May. I paid $4.59 at my local Costco. 87 was $4.19, so much better than the other Top Tier stations around here.

Baldeagle

Perhaps I am interpreting your statement incorrectly, but it seems like you are saying that only 91-octane fuel is "blended with a proprietary detergent additive" and 87-octane fuel is not. In turn, that is a reason to use higher octane fuel over lower octane fuel.

My understanding is that gas companies (Shell, Costco, Exxon, etc.) blend the exact same level of additives into 87-octane fuel as they do 91-93 octane. Higher octane fuel does not keep your injectors and combustion chamber any cleaner than lower octane fuel. It is the same. Therefore, the use of 91-octane is ONLY for improved efficiency (performance and fuel economy), however small that may be. If that is what you said, apologies in advance for implying otherwise.

fiatlux

It’s now just a 2 cent spread across grades at this station in downtown LA.

JB in AZ

Heh! That's likely because the prices here are all bogus.

fiatlux

I can assure you this is real. There’s also a Mobil station outside of the Beverly Center that’s at 7.25 a gallon and a 76 in Beverly Hills that’s at 7.54. Granted those are stations that are normally almost a buck higher than everyone else to begin with.

russianDude

How much more does it actually cost to make 91 vs 87?

Unobtanium

Just filled up with TT 91 octane, $3.75/gal.

Texasrdx21

Absolutely just nuts! Add in the President wants to take another 50 million barrels of oil out of the federal reserve - well, we use 20+ million barrels a day in the USA - that's not even a drop in the bucket a yearly basis. BTW - we as a country have to replace anything taken out of the federal reserve storage at todays prices - for emergencies and national security.

ross7777

Just remember when this happened back in 2008 the prices came back down to earth about 5 months later. Oil is a global commodity and world events affect the price no matter where you live.

Type X

i actually read that some states are 91 and some 93 for costco premium

when i had my crv i would get regular there but now with the rdx i run bp 93 with the ktuner flash

Running errands i passed by a costco today there were 10 lanes of maybe 70 cars deep n ran so long it left costco lot and into walmart next door

was nuts!

Pair of TLs

You are correct, sir!

bdawwg

Energy crisis incoming, if not already here. Hope everyone has the option to work remotely.

Pair of TLs

Right on crisis, wrong on remote.

Time to wise up on our energy consumption and tighten our belts.
Like doing convoy laps around the DC Beltway?

JB in AZ

My point, that I didn't make very well, is that at a 2 cents spread between octane levels, it seems that the price structure at the station is bogus. They probably decided they need to charge $6.99 for premium, and just made the other levels 2 cents apart. Just seems odd...But then everything is odd right now.
I'm not denying the $7 level.

One time I was at Sam's Club filling up with regular, and there was a tanker there. He glanced over and said "good, you are filling with regular, I am pumping premium into the regular tanks" LOL

Pair of TLs

Offloading premium into regular tanks isn't uncommon in the gas biz, but the other way around is illegal.
FREE 0.001% OCTANE BOOST!

EFR

Well, when our daughter turned 16, we gave her a new Mazda SUV, and the 7-11 tanker driver offloaded diesel into the regular tank....of course not being a diesel it turn out so well.

DAC17

Which tells you how much other gas dealers are ripping off users of premium. I guess because they can.

DAC17

The good news is that events causing this are at least not causing us to have bombs rained down on our cities and towns.