twinkieB25

i been put in shell 93 octane with 10% ethanol in my rdx since i bought my rdx, but i found a gas station that haved 93 octane 100% gasoline, that day i was running on empty and fill it full (16gal). i notice that my car response better and i got 4 extra miles to the gallon. now my question is, is 93 octane with 10% ethanol better or 93 octane 100% gas better or are they the same????????????

cwepruk

First off, A lot of gas has ethanol in in even if they don't advertise it. Gas with 10% Ethanol has slightly lower energy content, but no where near 4mpg gallon better. I beleive the number is something like 3% less energy.

Otherwise, octane aside, Ethanol is decent for removing moisture in the fuel system in cold weather and doesn't really have any benefits other than an octane booster.

corduroygt

I thought ethanol replaced MTBE, a harmful chemical.

MMike1981

i didnt know you could fill up in the states with a 100% gasoline product...?

wrestrepo

+1

twinkieB25

thx for the info and i talk to the gas sataion owner and he said his gas contain no ethanol in them only 100% gas with no ethanol in them also check this website http://www.americanfuels.info/2008/0...ing-extra.html

wrestrepo

I read part of that link and didn't really understand...

So, only 87 octane gas is 100% Gasoline? if so, you should NOT be using it.

wspy

You shouldnt be using 87 reguardless! Ethanol or not, the octane rating is the deciding factor.

John E Davies

Found this on Quora, it is worth thinking about.

“If you consistently fill a “premium only” car with regular, not only does this defeat the purpose (as mentioned below) of owning a sportscar, but you do run the risk of that knock sensor failing, and causing major engine damage. It’s a very small risk if you only do it once or twice, but if you do it over and over again, the cumulative risk increases. If you buy enough lottery tickets, statistically, you will eventually win… except this is the kind of lottery where your engine blows up and you’re on the hook.

If the dealer/manufacturer can prove that you were using regular gas, the warranty would not cover you for damages to the engine, and you would be responsible for the repair (even though the damage was partially caused by the failure of the knock sensor). This is because the warranty language specifies that in order for the warranty to be in effect, you have to maintain the vehicle according to the specifications in the owners manual (e.g. change the oil, and use the right grade of gas).

Short of testing the gas, there’s no way for them to know, but you can bet that if you bring in a 2 year old leased BMW with a blown engine, the first thing they’re going to test the gas, check the oil levels, and make absolutely sure the failure is their fault before they repair it for free”

https://www.quora.com/If-you-lease-a...-if-you-didn-t

I wouldn’t hesitate to put a lower grade in the tank if Premium was unavailable. Once or twice. Do you feel lucky?

John Davies
Spokane WA

DaIll1

I use premium and add Aces IV from BND ACES Formulas « BND Automotive for a little extra yeehaw

ColoRDX

Acura does not state what the "right" grade of gas is. They only "recommend" 91 octane. No where do they state 91 octane is "required". Page 527 of my 2021 RDX Owner's Manual does state
"Use of gasoline with a pump octane less than 87 can lead to engine damage."
It sounds like your quora blurb was written by an oil company.

JoWeJC

So we shouldn't be using regular gas? I think like 1 time a month i would fill up with the premium but these gas prices are ridiculously high these days!

Tomtwtwtw

You should avoid anything below 91 unless 91 isn't available. If you are running 87, I'd try to avoid high load on the engine and you'll reduce the risk of detonation.

Acura TL Racer

^

87 is okay so long as you drive softly. the ECU will account for the difference in octane. But if you want to drive on hills/mountains or normally/spirited-like, 911 is highly Advised. I used reguar in my wifes 2012 MDX and it didnt like accelerating at 2/3 throttle. and I felt hessitation and a resistance to upshift to higher RPMs vs. using 91 octane fuel. Didnt want to try this test in the 3G TL.

acura1972

I never went lower than 91 since I had the vehicle (over 10+ yrs). Sometimes even went to 94(or was it 93?) but then Sunoco became scarce(r) here and (I think) had up to 10% ethanol eventually (not 100% sure). Thereafter, I just stuck with Shell's 91 from then till now. My thinking is that the older the vehicle, the less "margin of safety" you have with these things.

Showkey

There is a KNOCK a sensor……..so there is NO POSSIBLE chance of detonation.

Tomtwtwtw

There's always a chance at detonation, but feel free to roll the dice.

DaIll1

and there is a sign that says Speed Limit...

deepa1600

You have a very different car, 2021 RDX is not same as the first gen RDX. That being said it does says in our 2010 RDX owners manual and fuel cap that 91 octane is required. Only use 87 temporarily if no 91 is available and long term use of lower octane gas will cause engine damage.

DaIll1

feralcomprehension

That quote is mostly garbage. It's true that you'll not get full performance, but modern machinery is designed with "foreseeable misuse" in mind.

1. The article seems to imply that using the wrong gas can cause your knock sensor to fail. Bullshit.
a) If they meant to imply that the danger resulting from a failed knock sensor was increased, I can buy that, but such a failure is likely to be detected and flagged.
2. This is fear-mongering: "If you buy enough lottery tickets, statistically, you will eventually win… except this is the kind of lottery where your engine blows up and you’re on the hook. "
3. I absolutely believe that the BMW dealer will do whatever they can to avoid warranty service.

feralcomprehension

Also nonsense. The expectation is that the knock sensor and corresponding algorithm is tuned so that it can hear knock when it first occurs and step in (typically reducing spark timing), but knock is inevitable with performance machinery and modern gasoline. The new Raptor motor has 4 sensors (700HP blown V8); not to eliminate knock, but rather to keep the engine safe by reducing performance if/when it starts.

hori

people saying 91 feels more powerful ..lol.. premium fuel is only needed for high compression premium engines. My street bike has a compression ratio 13.9:1 from factory and runs fine on 91 and was raced on track almost all it`s life banging off the rev limiter and guess what it runs perfect on the required 91 octane. Yes you heard that right Kawasaki high performance engine with 13.9:1 compression runs fine on required 91 octane. My RDX runs fine on the required 87 octane.

DaIll1

A turbocharger adds compression by forcing more than one atmosphere into the chamber before the piston starts moving up.

Baldeagle

Just for the purpose of discussion, Mazda’s N/A, 2.5-liter Skyactive engine has a 14:1 compression ratio and uses 87 octane. ECUs have tremendous flexibility today to control knock.

Tomtwtwtw

Where does the owner's manual say 87 is required on a first generation RDX?