I filled up the tank with 87 Octane by mistake in my 2005 325XI. I haven't noticed anything after a day or two of driving. Two questions - Can any damage result from one tank of 87 Octane? And, if I can't notice any difference in performance, is Premium really necessary? Whether or not it is necessary, of course I will continue to run Premium just to be on the safe side. Just curious.
87 Octane by Mistake
- Thread starter sidney
- Start date
You're fine. Yes, you'll notice the acceleration will be markedly more sluggish. But the engine has anti-knock sensors and will adjust to the lower octane. The BMW mechanic in Roundel said he will use the lower octane on long road trips when the engine is at peak operating temperature and low loads because on long straight-aways the engine apparently doesn't much benefits of the higher octane. But he recommended getting back to the premium by the time time you are in city driving and cold start ups. So one tank of the lower grade is not going to ruin your engine. But it is not recommended often and I would probably top it off with premium as soon as you have some room in the tank.
This might be a good time to add some Trecron fuel injection cleaner...even though it's best to add it before you fill up.
This might be a good time to add some Trecron fuel injection cleaner...even though it's best to add it before you fill up.
I've never felt any difference (either in power/responsiveness or at the pump) after using Techron or any other fuel injector cleaner in my car. Either my fuel system is extremely clean (doubtful with 275k) or totally gunked up beyond what a fuel injector cleaner can do (also doubtful since the car runs great).
I guess I'm just a little skeptical about what a bottle of fuel injector cleaner can actually do to clean the fuel system.
I guess I'm just a little skeptical about what a bottle of fuel injector cleaner can actually do to clean the fuel system.
The high octane requirement of our engines is due to their higher compression. The more you compress gas and air, the more likely they are to pre-ignite. Ignition just from pressure and heat, before the spark. That is pinging , knocking or detonation that everyone talks about. So.........the use of 91 or higher in our engines will help prevent this pre-ignition as the higher octane gas has a higher ignition temperature, so in our high-compression BMW engines, this is a must. Also, the same applies to all high performance, hence high compression engines.
Correct me if I am wrong.
BTW I agree that the one tankful of 87 will not harm your car as the ignition will be retarded as the engine senses the pre-ignition that WILL occur, but you won't get the full performance BMW intended and spent those long painstaking hours designing into your engine when your spark is retarded to compensate for the lower octane fuel.
Correct me if I am wrong.
BTW I agree that the one tankful of 87 will not harm your car as the ignition will be retarded as the engine senses the pre-ignition that WILL occur, but you won't get the full performance BMW intended and spent those long painstaking hours designing into your engine when your spark is retarded to compensate for the lower octane fuel.
![[hihi]](/images/smilies/icon_smile_hihi.gif "Hi Hi [hihi]"){kind=icon}
i guess i dont' even need to chime in on this one eh? ![[;)]](/images/smilies/wink.png "Wink [;)]")
def not the end of the world. in fact, it might help w/ your cold starts from what i heard from my service rep. (contradictory from what Scott's (aNoodle) guy was saying..) and when i say cold starts, i mean ones in the sub zero temps, not the typical "cold" starts down south.![[:p]](/images/smilies/tongue.png "Stick Out Tongue [:p]")
def not the end of the world. in fact, it might help w/ your cold starts from what i heard from my service rep. (contradictory from what Scott's (aNoodle) guy was saying..) and when i say cold starts, i mean ones in the sub zero temps, not the typical "cold" starts down south.