Hey all,

I just got a brand new G37x and its my first premium car. I'm completely aware of the reasons why premium fuel is required and I would never intentionally put the wrong fuel in and sacrifice performance. However on my first fill-up, I wasn't thinking and out of habit filled the entire tank with 89 octane. I understand that the ECU will adjust and reduce the engine's performance or there will be knocking so I was curious if accidentally using one tank of 89 fuel will cause any lasting effects on the engine's performance. Will the ECU readjust when I fill my next tank with 93? Again, I understand the ramifications of using too low of an octane, I just wanted to make sure I didn't permanently screw up my new car and was concerned whether or not the engine would correct itself and return to proper performance levels. Thanks a lot!

 

There will be no lasting effects.. don't worry. Enjoy your car!

 

also wanted to add on : new car has a break in period, you better check with dealer schedule for a maintenance check~ It wont getting anything wrong but com on man, this is a brand new car, I just got mine in Sep as well.. take good care

dont worry this time!

 

It will be perfectly fine, just use 91+ from here on out. It will not do any damage to your car. You will have some people probably respond that they use 87 octane all the time and their car is fine.

 

Your car will be perfectly fine. It's smarter than you. All that will happen is that your timing will adjust and effectively reduce the compression ratio so that you don't get any knock. Won't get as much power out of it as you could, but it won't hurt anything.

And when I read the thread title, I thought you mean diesel instead of gasoline, which would undoubtedly cause some problems.

 

I also have a 2011 sedan 6 mt and I have put 91 and 87 on different occasions. I really don't see any difference in either. The gas mileage remains the same - 20.4 - no matter how I drive, aggressive or passive. I am not tracking the car or driving like my hair is on fire everyday, however, I do rev the engine up and reach 5-6 K rpms frequently. In short, I do not notice any difference in the car's performance using 87 octane fuel. I have 5K miles on the car.

 

I had a friend who drove her Lexus ES300 using 87 octane all the car's life (back from 1995 to 2001). At about 100k, she asked me why her car felt so slow..... As soon as she realized the car required premium, she started using that. Next time I talked to her, she was amazed that her car ran so well. 100k miles on regular and the car sprung back.

I think your car will be fine, like everyone else said.

If you are really, really really **** then I suppose you can top the car off every 20-30 miles with premium to mix the tank out...... Just find a station that has separate hoses.

 

Lol. Not again!

 

just keep it at the 93 next time

 

Wow, I have no source for 93 within a reasonable distance. Must be nice
I doubt there'd be a measureable gain from using 93 over 91, but if the price isn't too crazy I'd give it a try.

 

You will be fine. Just burn it till the last drop and refuel.

 

Since it's new you shouldn't be driving it real hard, anyway... so drive it fairly easy (I wouldn't go over 5K rpms) and filler 'er up with 91 when you're out. It will be fine.

At Sewell Infiniti Dallas they fill up all their cars with 87 octane. I saw the pump they use behind the used car building. My sales guy said they all use that pump on all their cars, and they get free gas in their "demo" cars which the dealers drive until about 5,000 miles, then they sell them at a discount.

Heck, I bought one, saved thousands, and my car is in perfect shape and runs like a bat outta' hell. Today, I mix 1/3rd tank of 87 octane with 2/3rds tank of 93 to get the required 91 octane. Saves me a couple bucks per tank.

 

omg dude!!! quickly jack the car up and screw the little gas tank plug off and drain that bishh!!! then run really hot water threw the tank to rinse it out and let it air dry for a week under the sun!!!


if you do it right the car wonr blow up!!!



im just kidding man, welcome to the club, you be ok just drive it till empty and fill up with 91+.

 

at this I thought the OP pumped diesel fuel..... that would be bad. My friend's sister did that once and they had to tow the car to Lexus, have the tank drained and fuel filters replaced. $800 mistake.

 

When its half empty, top it off with 93 octane and you'll be back in speck. 89+93/2 = 91