will using 1 tank of 87 octane gas damage the engine significantly? someone else 'mistakenly' filled the tank with 87(about 30Liters?). its already been used up and filled back with 91. with that in mind, ive currently used about 15Liters so far and today suddenly while i was driving i feel these pulses (i would say experience is like brake judder but it happens with a noticeable noise and a good pulsating/revolution thumps)

at first because of the interval-ed like thumps, i thought something was stuck/wrong with my wheels but it was fine. opened the hood and gave it gas and i could hear it. and when i reved it to like 4k(can hear slightly{at Park}[can hear it much more/stronger when its in Drive]) and let the pedal go, at about 1.4kish the needle hesitates a milisecond while creating a bass-like thump and goes to idle rpm which at this point its 'normal'

ideas? going to dealership tmrw, itll probably be under warranty right??

the car has used regular gas before once or twice and it was fine.
oil changed every 6000km

 

Don't think regular gas will have such drastic effect, so it probably would have occured even if you hadn't used reg gas. Let us know what the dealer says is the cause of it.

 

I am kind of curious now on what happen to your car. Let us know please.

 

hmmm thats weird i dont think using regular gas would have cause that problem there barely a difference in 87 and 91

 

i've used 87 in mine with no problems...

 

Its fine... just don't do it alot. If this was the case, all the g37 loaners would be dying ... I don't use premium on disposable cars XP