What do I do if I accidentally put regular gas in a premium car?
Posted by Street_Firefighter_7@reddit | askcarguys | View on Reddit | 103 comments
I guess when I bought the car luxury didn’t stand out to me. This is my first car ever it’s a 2016 Acura ILX. I’ve been putting regular gas in it for about a year and wondering why my mileage is shit. Well I was today years old when I found out it took premium gas. Ugh. What do I do from here? It has about half a tank left of regular gas. Please help, sincerely just a girl with no male figures in her life.
omg4serious@reddit
fill it up with premium and go about your day.
it's unlikely to cause any damage unless you do it long term. and you'll notice knocking/running rough if there were issues.
PetriDishCocktail@reddit
Just an FYI, there's a little sticker on the pump that says something like..."[this fuel meets federal air quality standard and maybe used in all motor vehicles...]. Part of that law is that the automaker must conform to the fuel at the pump, not vice versa. Therefore, the car will automatically adjust the computer and the timing to use a lower grade of gasoline. It's how they're built. It's part of the emissions laws. It is 100% safe to put whatever fuel is available at the pump in your vehicle.
Let me give you two examples... A few years ago Ford offered the Mach mustang. With premium fuel it made 426 horsepower. If you use regular it only made 420
Recently, the Mazda 3 turbo is rated at 250 horsepower, but only 227 with regular fuel. But, the torque number stays the same no matter which fuel you put in. These two examples illustrate that the computer will adjust.
R2-Scotia@reddit
I have a US market car that will NOT run on regular, needs at least California super (91 AKI)
Choice_Branch_4196@reddit
"It is 100% safe to put whatever fuel is available at the pump in your vehicle."
Or pumps have diesel and gas. Absolutely cannot mix those two 😂
Youcants1tw1thus@reddit
You’re going to get angry downvoted by the mob of “my car needs premium” jackasses.
SockeyeSTI@reddit
My STi and its weak ringlands that are sensitive to knock would like a word
Youcants1tw1thus@reddit
That’s just what makes a Subaru a Subaru. Fix the horrible factory tune that leans it out too much, that’s the major issue. Lower octane just flushes it out so you notice it more.
NuclearHateLizard@reddit
Imagine if everything in life worked like it's supposed to on paper
Sideburn_Cookie_Man@reddit
Which is funny, as 91 is the lowest option here in Aus.
Donkey_Ali@reddit
Like everything else, America measures it differently from the rest of the world
Healthy-Theme8261@reddit
That's what she said
jabeith@reddit
They've got Canada and Mexico in their corner on this one
scuzzy987@reddit
We're special and not in a good way
LongOrganization7838@reddit
Austrailia uses RON US uses AKI, RON(Research Octane Number) is determined when the engine is under light load to simulate intercity driving
AKI(Anti Knock Index) uses the average between RON and MON(Motor Octane Number)
MON is determined when the engine is under medium and heavy loads to simulate highway driving
The US has the largest and most extensive highway system in the world and US drivers spend significantly more of their time at highway speeds
omg4serious@reddit
man 87 is typical for the usa. some places even use 86.
scuzzy987@reddit
I saw pumps with 85 octane out west but was not sure if I could use it when my manual said use minimum 87
Alarmed_Champion_302@reddit
High altitude regions have 85. The air is thinner so your compression is lower. Highly compression is what drives the need for higher octane to prevent pre ignition/pinging. If your engine is naturally aspirated, its compression will drop with higher altitude.you can use 85. If its turbocharged, the turbo keeps compression the same, one reason why they are so great in the mountains, but you'll need to run 87 or whatever the manual calls for at all times.
Sideburn_Cookie_Man@reddit
Yeah it turns out that the octane ratings we use are different too, so the numbers don't even line up
ZephyrStudios686@reddit
yeah its not comparable
SirisC@reddit
91 on the RON octane scale and 87 on the AKI octane scale are roughly equivalent.
YeahIGotNuthin@reddit
You guys measure it differently. Your 91 octane is the same as US 87 octane.
Street_Firefighter_7@reddit (OP)
It says premium recommended when I open the fuel cover but I never saw that until well, earlier today when I checked something
HeavyProfessional420@reddit
I run 87 when in Mexico just change to 91 at half tank btw I wouldn’t recommend anything less than 89 long term since it has both, plus 91 only little more anyway
Goingdef@reddit
Just go fill it up, it’s been almost two years you aren’t fixing anything at this point because you didn’t break anything but you will see an eventual improvement in mpg might take a tank or two for the car to relearn that it’s no longer combating knock.
Muttonboat@reddit
Push comes to shove buy octane booster
ClickKlockTickTock@reddit
Actual octane booster, not the gumout bs walmart sells.
And even then, I've fouled spark plugs and CAUSED misfires by using that shit.
Youcants1tw1thus@reddit
No, you haven’t. You can try to explain if you want, but that’s not how that works.
shaysauce@reddit
Likely nothing. But also lower octane in an engine designed for higher can lead to some engine ping - ESPECIALLY in turbocharged motors.
Don’t make a habit of it but also don’t worry you’re not going to like blow up your engine lol.
TheKoziONE@reddit
You will be fine, car will adjust and reduce performance. Just add some premium later.
tomz17@reddit
To be fair, it can only do that after it detects a knock. So this is not really meant to be a long-term solution, but more of a, "I am stuck in the middle of the desert and there is no premium gas around, kind of solution."
JCDU@reddit
Knock sensors are insanely sensitive though, any car built in the last 20+ years will be absolutely fine on regular gas with zero ill effects - it will just retard the timing and run with slightly less power.
Sideburn_Cookie_Man@reddit
Top it up with premium, and then use premium from now on.
Youcants1tw1thus@reddit
What if all they have is super premium deluxe?
Come on, car guys use actual fuel ratings and not dumbass sales pitches to describe octane.
theyoyomaster@reddit
I’ve seen 89 be called “super” in the US…
Sideburn_Cookie_Man@reddit
It's worth keeping in mind that octane ratings don't carry across countries.
US 87 is equivalent to AUS 91 octane, for instance.
Youcants1tw1thus@reddit
Which is why we denote RON, MON, (R+M)/2
Sideburn_Cookie_Man@reddit
Yup, but most consumers have no idea what those even are.
That's why we use colloquial terms like premium etc.
Youcants1tw1thus@reddit
But they need to know, because most of the cars that say “91 minimum” actually specify which test and that changes what you may actually need at the pump in your country.
Sideburn_Cookie_Man@reddit
Yeah, except they don't care. Low effort consumers are a funny sort.
Youcants1tw1thus@reddit
Don’t stoop to their level. We have enough idiocy.
Sideburn_Cookie_Man@reddit
There's a lot of value in communicating with people on their level.
Fickle-Salamander-65@reddit
Nothing. Relax.
Tight-Unit656@reddit
Fellow 2016 Acura ILX owner here. Putting regular in for an extended period of time is not recommended. It definitely can affect fuel economy, but more worrisome is carbon build up. Switch to 91 now that you know.
Some maintenance to consider, I had similar mpg’s until I replaced the ignition coils and spark plugs. I believe it’s recommended at 100k. I’ve been back up to 25 City/36 HWY ever since. A good set of tires will also help.
SnooLemons9175@reddit
Nothing, you might get a bot less power, but its not going to do major harm to your car. Just fill up with the recommended fuel in future. Its not like you've pit the wrong fuel in, ie diesel instead of petrol.
PulledOverAgain@reddit
Nothing
Newer cars will figure it out and it will run fine
sheepforwheat@reddit
It turns into a Honda
_null_null@reddit
If the tank isn’t completely full, add some E85 ethanol?
I’m not a car expert but that will raise the equivalent octane.
rjlawrencejr@reddit
Drive.
NYOB4321@reddit
If it says premium required, use premium.
If premium recommended then you decide which one is best for your circumstances.
My vehicle says premium required.
Zbunny666@reddit
Hey girl, I’m a girl too!
You should be fine! Usually, you get some detonation when you use lower grade fuel which is a popping noise when you accelerate. If you’re hearing that, just know it’s harmless and goes away once you start using premium. Either way you haven’t done any permanent damage and your mileage will improve!
Longjumping_Dark3827@reddit
Just wanted to piggy back on the detonation. You are correct in this specific car the only real risk its running is the detonation, but detonation isn't exactly harmless.
tbe detonantion can damage the cylinder head, all the early explosions occurring where they shouldn't be could cause wear where it shouldn't be. head gets an uneven almost grainy texture and can even pit, which compromising that surface could then cause other components to fail
running 87 in a car that calls for 93 isn't a guarantee death sentence like running 87 in a diesel would be, but it fs could still cause permanent damge
JonnyGee74@reddit
Depends if it's a turbo car or high compression, or otherwise high performance. With some of my cars, it would be a major problem. With other cars it really doesn't matter if you don't stomp on the gas.
ThatOldEngineerGuy@reddit
Drive it easy and keep topping with premium.
Green_Replacement573@reddit
Best advice I’ve see here. Low load. No flooring it, down shift and don’t lug the engine in the lower rpm
Small_Aardvark_5496@reddit
No big deal. Drive it. Put gas in as soon as you get to 1/4 a few times and dilute it IF you notice any drivability issues. Modern cars have knock sensors though that retard the timing if you get any knock, so all that happens is a bit of a loss in power but nothing serious.
Specialist_Okra4080@reddit
Keep driving
ssevcik@reddit
It makes very minimal difference on that engine.
FaithlessnessEasy276@reddit
Just switch to premium going forward
Inevitable-Notice351@reddit
Buy a bottle of octane booster and it will immediately smooth things out and make it run as if you put premium in.
Imaginary_Golf7211@reddit
I put regular gas by mistake in my wife's Volvo. As I have always read-the computer retards the timing-making the car slower. That's exactly what happened. It was sluggish-but ran OK.
yarsftks@reddit
Should be fine. Just add premium and mix it in.
DonkeyImpossible316@reddit
I mean if its run my turbo 911 out of gas or run some regular gas? Def going to run some regular gas. Even if is some cheap shit. That being said, I dont cut it close. I wouldn't be worried to run a tank of regular, just would not make it a habit.
Normally I run premium Chevron or Shell, Costco if the line isnt down the street.
I miss real premium outside of ca, that good shit like in Texas but it is what is is.
RealFlatworm-@reddit
It's totalled
ShoddyHorse_@reddit
Loose your mind and ask reddit before google.
Just go inside and grab a couple bottles of octane booster and dump it in your tank. You’ll be fine!
YankeeDog2525@reddit
Nothing. It will be fine.
HamsterCapable4118@reddit
Fun fact: dealerships never fill with premium. Even luxury car dealerships. So the very first tank was regular, and likely the cheapest gas available, not even top tier with detergent stuff.
And if it was ever a service loaner, it never saw a drop of premium.
And the people who owned the car before you almost certainly didn’t use premium.
Snoo59759@reddit
Better hope it has knock sensors to detect knock so it would pull timing and other things to prevent the knock from happening again
CougEngr@reddit
My first car, an ‘86 Volvo had knock sensors and a distributor. Certainly a 2016 Acura can adjust its timing
AlternativeAdagio164@reddit
I hear Mercedes is very sensitive if you put regular gas
TRex_Chef@reddit
Nothing. Marketing bs is still bs
unurbane@reddit
Depends on the ECU and tuning. Some cars are fine, some will knock.
TRex_Chef@reddit
Sounds like a failure of engineers
unurbane@reddit
That’s not a failure lol. Those are specs written for engineers to follow. Cars like the Si or WRX require a higher compression ratio as the foundation to the design of the engine.
TRex_Chef@reddit
Then show me the failure rate of not doing so. I keep.m reading engineer bs speak and no one actually shows evidence it has a significant effect.
unurbane@reddit
Dude you’re ridiculous. Some manufacturers say do t do it, so don’t. Some are tuned for FlexFuel or 87 or 93 it doesn’t matter because the ECU accommodates it.
TRex_Chef@reddit
Still waiting fornl actual data. "Manufacturers say" is marketing bs. Keep.changing the argument though. Its fucking hilarious.
GMAN7007@reddit
It's not bs, the car won't perform as usual with lower octane fuel. It might not be a big difference but it would be different.
TRex_Chef@reddit
I dont believe you.
GMAN7007@reddit
How will I ever go on?
TRex_Chef@reddit
I.honestly dgaf. You're just speakjng out of your ass.
Data > bs
TheVillianOfValley@reddit
Premium recommended: you can run Regular if you want, but you’ll enjoy your vehicle less.
Premium restored: if you run Regular, you will damage the engine.
Yours is the former. So no big deal.
s92e92spen15a55t1ar@reddit
Just go easy on the gas pedal, and add premium whenever u can. It'll be fine.
Clear_Date_7437@reddit
Well every rental car in the US would be cooked, so no worries. Will you be short a few HP yes but no harm done, but mileage differences between will not be radical to the tune of 5mpg.
NHRADeuce@reddit
It's unlikely that you will get enough extra MPGs to pay for the difference in price. Premium is recommended, but it will run fine on regular.
lpg975@reddit
Drive it lightly until you can fill up a full tank with premium again. Modern engines have knock sensors that will pull timing to reduce the risk of engine damage from predetonation. Your car will live, just don't do any WOT pulls. Baby it. Drive like a grandma. You'll be fine.
Timely_Maybe479@reddit
it’s going to explode. give me the keys and i’ll make sure it’s disposed of properly 🤣
IndicationCurrent869@reddit
It's fine, the car electronics will adjust the engine. Refiill gas early if it bothers you. Just don't put in diesel by mistake 😵💫
JimmyCradle@reddit
It will become regular.
redditorrrrrrrrrrrr@reddit
Not a big deal.
If worried they make octane boosters or just fill it the rest of the tank with premium.
Electronic_Cress_278@reddit
Octane is all about compression ratio. Most 8.5-1 to 9.5-1 are fine. A 10-1 needs 93. It's a rating of its ability to not per explode
Leverkaas2516@reddit
Do you mean not pre-detonate?
OP, this is not about your engine exploding
Coolmacde@reddit
You'll eventually ruin your engine.
SigmaINTJbio@reddit
I have a V8 Camaro that requires premium high octane fuel (LS3). On the forums, people who ran regular noticed a decrease in performance. The ECU retards timing to prevent knock (pre-ignition), but will readjust after a few tanks of premium. There are tricks to reset the timing table sooner, but your Acura may do the same. Use premium now, and from ow on and you should see improved power.
PaleontologistNo7941@reddit
Just don't rip it around wide open throttle
AZHawkeye@reddit
Just start using premium. The computers will adjust accordingly. Learn about all the sensors in your vehicle and what they do. It might alleviate some of your anxiety about this. Cars with turbos behave a little differently when not using premium, so you should be OK with your NA engine.
Electronic_Cress_278@reddit
I have to run 93. In my truck but my car is recommended for 87. Using anything more than 87 is doing nothing positive for the car but costing more $
TheRealWhoMe@reddit
Just use premium for now on, unless you are in a jam. Using the lower grade isn’t the end of the world, but the car will run rougher and have reduced performance.
Unlike using the wrong blinker fluid, it shouldn’t cause permanent damage. /s
WiseSubstance783@reddit
You just need to call the tow truck.
GMAN7007@reddit
That's absolutely not true quit your bullshit you don;t know what you're talking about.
WiseSubstance783@reddit
Easy cobra…
funtasticassembly@reddit
Drive it easy, burn the gas and don't worry too much. The car will detune itself and your power will be down and the consumption will be higher but as long as you take it easy- no full throttle redline runs etc it will be ok.
GMAN7007@reddit
It would be fine anyways. If OP really wanted to they could just add an octane booster. Other than doing that they ca drive the care the same way it might just not have the HP they're accustomed to.
JustaYnLivin@reddit
Its ok to mix it will just lower the octane to 89 or 90, or ust drive until low gas light comes on then go full up on 91. it's not necessary though you been using it for a year you just weren't getting all the power it is rated at. Fuel economy won't change higher octane doesn't do that, it just prevents detonation before its supposed to in the combustion cycle.