WHY 91 Octane Fuel for Acura

Joined
Jun 17, 2013
Messages
1,607
Location
USA, FLA
I have a 2015 Acura ILX 2.0 and it says in owners manual 91 Octane Minimum .. Mid grade is 89 and Sunoco has 91 and 93... Sunoco is the only place that has 91 and what crazy is the 91 octane costs more then the 93 ULTRA.,,, Anyways... Most places have 86 regular and 89 Mid-grade and 93 Premium. I tried 86 Octane when I first bought the car and it ran fine but I have been told that it will cost me in the log run... So I have been using 93 Octane... However the HONDA CIVIC is basically the same as the ILX.. I'm pretty sure its the same spark plugs and coils if you look up the same year and engine.. I have not done that yet but Im going to . However the ACURA Says on the gas tank door PREMIUM FUEL ONLY... Not Recommended.... Says ONLY... Can anyone explain why??? Thanks P.S Also I was told not to use Regular / 86 and then put Octane booster.... That would be bad to do with each fill up.
 
Last edited:
Joined
Oct 30, 2015
Messages
835
Location
Wisconsin
My guess is that Honda and Acura use (slightly?) different tuning/programming on these models. I know Toyota and Lexus do. Perhaps the HP/torque figures differ; this is an easy way to tell. Also may have something to do with the fact that Acura and Honda get different target markets. Honda drivers may be stereotyped as frugal, and might balk at having to use premium gas. Acura drivers are stereotyped as more affluent, so more generally would be ok with using more expensive gas. This is likely accompanied by a tuning difference of some sort - the Acura engineers can push the envelope a bit further, perhaps... I wouldn't fret about finding 91, I would just use whatever "Premium" is in your area. For us, there are stations with 91, 92, and some at 93. My experience on the east coast is that most stations had 93, so I'd use that and sleep well. I haven't seen 86 east of western Nebraska and/or South Dakota; are you sure that's not 87 as your regular grade rather than 86 you are seeing? That's more of a high-altitude thing, in my experience.
 
Joined
Jun 12, 2004
Messages
2,986
Location
Athens, GA
Depends on the Civic. According to what I'm seeing, the K24Z7 in your ILX was only used in the Civic SI, and according to its owners manual, it requires 91 as well. The 1.8l motors of that era called for 87. You would probably be fine with 89. I alternate between 89/93 and ethanol free 90 on a fairly regular basis with no rhyme or reason in my TL which also calls for premium only. I might notice a small hit in mileage but I never notice any pinging or performance hit. Try the 89, if you notice bad things, go back up to 93. The car should be smart enough to figure it out. As for why? TmanP pretty much nailed it.
 

David1

Thread starter
Joined
Jun 17, 2013
Messages
1,607
Location
USA, FLA
Originally Posted by ctechbob
Depends on the Civic. According to what I'm seeing, the K24Z7 in your ILX was only used in the Civic SI, and according to its owners manual, it requires 91 as well. The 1.8l motors of that era called for 87. You would probably be fine with 89. I alternate between 89/93 and ethanol free 90 on a fairly regular basis with no rhyme or reason in my TL which also calls for premium only. I might notice a small hit in mileage but I never notice any pinging or performance hit. Try the 89, if you notice bad things, go back up to 93. The car should be smart enough to figure it out.
Yes I forgot to mention at SHELL they have ethanol free 90 octane and actually the Acura runs best on that.... and its about the same price as the 93,. but the 93 has ethanol and Id rather not use ethanol . I have been told ethanol doesnt even burn it just goes straight through the system and its actually bad for engines... I remember in the late 80s and 90s all gas was ethanol free and then citgo starting using ethanol and then you started to see some s gas station have signs saying 100% GAS... Now they all have it .. other then SHELL and WAWA and a few other places. However Yes.. I really like the ethenol free 90 octane... I actually get the best fuel economy out of it. Ill try what you said and alternate from 89 / 93 .. However Im still thinking about only using 90 E Free fuels but no all gas stations have that around here... just 2...
 
Last edited:
Joined
Feb 12, 2008
Messages
1,265
Location
PA
They sell 86 octane in FL? Unless you really push the engine 89 should be just fine. I'm sure you can use a digital gauge to see if the engine is retarding timing at all when using it.
 

David1

Thread starter
Joined
Jun 17, 2013
Messages
1,607
Location
USA, FLA
Originally Posted by TmanP
My guess is that Honda and Acura use (slightly?) different tuning/programming on these models. I know Toyota and Lexus do. Perhaps the HP/torque figures differ; this is an easy way to tell. Also may have something to do with the fact that Acura and Honda get different target markets. Honda drivers may be stereotyped as frugal, and might balk at having to use premium gas. Acura drivers are stereotyped as more affluent, so more generally would be ok with using more expensive gas. This is likely accompanied by a tuning difference of some sort - the Acura engineers can push the envelope a bit further, perhaps... I wouldn't fret about finding 91, I would just use whatever "Premium" is in your area. For us, there are stations with 91, 92, and some at 93. My experience on the east coast is that most stations had 93, so I'd use that and sleep well. I haven't seen 86 east of western Nebraska and/or South Dakota; are you sure that's not 87 as your regular grade rather than 86 you are seeing? That's more of a high-altitude thing, in my experience.
Yea I think you are correct... Im sorry its 87 octane.... I dont use regular anymore so I forgot the octane... LOL.. sorry about that. I remember the good ole days when SUNOCO had 86 Economy and 87 Regular and 90 Mid / aka PLUS and 91 Super and 94 Ultra... That was in the good ole days.
 
Last edited:

David1

Thread starter
Joined
Jun 17, 2013
Messages
1,607
Location
USA, FLA
Originally Posted by umungus1122
They sell 86 octane in FL? Unless you really push the engine 89 should be just fine. I'm sure you can use a digital gauge to see if the engine is retarding timing at all when using it.
Yea Im going to alternate...... 89 and 93 and when I can use the 90 E FREE... What about useing 87 regular and adding Octane booster??? I was told thats not good to do.. What do you think?
 
Joined
Feb 12, 2008
Messages
1,265
Location
PA
Originally Posted by David1
Originally Posted by umungus1122
They sell 86 octane in FL? Unless you really push the engine 89 should be just fine. I'm sure you can use a digital gauge to see if the engine is retarding timing at all when using it.
Yea Im going to alternate...... 89 and 93 and when I can use the 90 E FREE... What about useing 87 regular and adding Octane booster??? I was told thats not good to do.. What do you think?
No to octane booster with MMT. It will foul plugs and cats. If you wanted to increase 93 octane you could add toluene or xylene, but both cost about $15+ a gallon. Just using gas from the pump seems best for what you want to do. https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=781023
 
Last edited:
Joined
Dec 23, 2011
Messages
197
Location
WA state, USA
Originally Posted by David1
...the 93 has ethanol and Id rather not use ethanol . I have been told ethanol doesnt even burn it just goes straight through the system and its actually bad for engines...
Ethanol doesn't even burn? no-no You should be fine with 89, 90 E0 or 93 as the owner's manual states Use of gasoline with a pump octane less than 87 can lead to engine damage.
 
Joined
Jun 28, 2012
Messages
3,288
Location
Southern Illinois
90 octane NON-ethanol would be the best. My 2019 Challenger Shaker 5.7/6 speed takes 91 octane. I put 5 gals 87 octane + 10 gals 93 octane for a mix of 91 octane. Runs great on this. I like the fact that I'm putting in 5 gals of known fresh fuel. Most stations around here only get 1500 to 3000 gals of premium once a month, sometimes a month and a half. Is the premium ok to use? Yes most probably, but I have gotten some bad 93 octane fuel. The car does not run any better on pure 93 octane either.
 
Joined
Jun 14, 2011
Messages
3,354
Location
Texas
Originally Posted by David1
I have been told ethanol doesn't even burn it just goes straight through the system and its actually bad for engines
Nonsense. Whoever told you this was wrong. You are overthinking this. Just use 93 Octane Premium E10 and don't worry about it.
 
Joined
Sep 10, 2008
Messages
441
Location
Cold Lake, Alberta, Canada
To the O.P.: Could you be confusing the gas cap sticker that says to "use premium fuel only" and an owner manual that says "91 Octane recommended" to mean you can only use 91 Octane? The "premium fuel only" sticker could be a way for Honda to get out of paying for anything under warranty if they suspect (or just feel like claiming) any drivetrain issues you might experience are caused by bad fuel. If they don't specify an Octane rating on that sticker it doesn't mean much.
 
Joined
Jan 21, 2011
Messages
2,378
Location
California
It may be the same basic engine between the Acura and Honda, but definitely a different application. So there are some different parts, perhaps high-compression pistons or (as another said) different engine tuning or computer programming.
 
Joined
Dec 22, 2002
Messages
718
Location
Ottawa, Ont CANADA
If you use 87.. your knock sensors are working overtime... as mentioned above, you may witness some pinging and knocking if you push it just a little.... its your engine taking the hit.. its youre call.. my 2c J.
 
Joined
Jul 21, 2013
Messages
920
Location
D/FW Metroplex
Let your right foot's lead content be your guide. If you never operate the engine at WOT, use any octane you want, the engine won't notice. If you're like me and believe a day without WOT is like a day without oxygen, use only 93 or whatever the highest octane is you can find. Your geographic location's hot/humid climate will be mitigated somewhat by the extra octane in the gasoline. If you mash the gas to the floor periodically for passing maneuvers and such, use the 89 at the very least and 91/93 octane as availability and finances allow.
 
Joined
Dec 4, 2004
Messages
13,225
Location
1/2 hr N.E. of Detroit
We bought a new 1984 Pontiac 6000 2.5 and kept it for 20 years. Here in Michigan, the next higher octane to 87 & 89 is 93 octane. If we didn't use 93, the Pontiac engine pinged. Outside of paying more for gas at the pump, it was a terrific car - that had so-few repair bills. Rust is what sent it to the graveyard. I drove it there
 
Top