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Discussion Starter · #1 · (Edited)
So my beautiful wife filled up her new GLA250 for the first time last night, and by mistake put in regular (87) instead of premium (91). :crying:

What should we do now? I see the options as:

  1. 1. drive it anyway
  2. 2. when it's down a 1/4 tank, put in premium, and keep doing that for at least 4 fill ups
  3. 3. put in an octane booster
  4. 4. drain the tank and put in premium (I hope this is not the only option!)

Please help!
 

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The ECU will pull timing, there will be a loss (enough to notice) of power, could experience rough starting, check engine light could come on and plugs could foul a bit.

I would just drive the car and at about a half tank fill with highest octane gas you have in your area and repeat at a half tank.

Should not be a big deal, but if the check engine light does come on or your getting a lot of pre-detonation (knock) I would take to to the dealer and have them check things out.
 

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I would not worry much about it but personally if I were in your shoes, I might put an octane booster, just make sure you research and get the one that actually works best. Some of the commercial octane boosters just doesn't do anything at all.
 

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Discussion Starter · #4 ·
I was thinking the best option was an octane booster. Anyone have suggestions on brands?
 

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The car will be ok, have had a lot of friends who lease their premium luxury sedan with the cheapest gasoline possible with not much consequence. Learn from it and move on.

hey at least it wasnt diesel
 

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Well, if you go the octane booster route, then the best out there bar none is Lucas Octane Booster. Problem, is not all automotive retail shops carry it, but always worth a try.
 

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Discussion Starter · #7 ·
I checked out octane boosters online, and most are "not street legal". Does that mean they may damage anything? Or are they just more polluting?
 

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Just CARB regulations I believe, it isn't going to damage your car. Other states sell up to 100 octane while others are only allowed 91.

I can tell you though that for my friends old 328i, he loaded it up with regular and got some knocking on the engine and put octane booster on it and it got rid of the knocking. This was years ago so my memory is a bit foggy and I don't even remember what booster he used but I do remember it working.

Maybe see if you get some knocking and then try it out if there is?

You are located in SoCal so I am sure it will be pretty easy to find, or once you are halfway through gas tank, drive to a gas station around race tracks that sells 100 octane and fill em up with that? Pricey though.
 

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Apparently it won't do any harm, all you'll experience is a loss in power till you put the proper octane back in.
 

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My brother leases his BMW 335IX. He is so cheap that he always puts regular in it and has suffered no ill effect in two years of driving. I wouldn't expect your GLA to suffer either. As noted here previously, the knock sensor input to the engine controller will retard timing. Only net effect is loss of performance until you get the octane back up. Based on my brother's car, the performance difference will be slight.
 

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I wouldn't worry too much. Either put in the octane booster or just top up the tank with higher octane fuel earlier rather than later to try to mitigate the effects. I would opt for filling up the tank once its half done personally.
 

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Discussion Starter · #12 ·
Update....

I've driven the car now 60 or so miles, and it seems totally normal in every way. I've even been driving in non-eco mode, with sport turned on. No problems at all. I will fill it up with premium when it's at about a half a tank, and then again at the next half a tank.

I didn't, by the way, add any octane booster.

Also by the way, WOW, what a sporty, punchy car that GLA250 is! In sport mode it gets up and GOES! I also have a 2007 Pontiac Solstice GXP as a comparison, and while my little GXP is definitely faster accelerating, the much bigger GLA is really impressive.
 

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Haha, yeah the GLA feels slow from a stop but once it goes then it goes for sure!
 

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Discussion Starter · #14 ·
Yeah, we've only got 600 miles on it, and I barely get to drive it, so this was the first time I got to get on it. Very nice!
 

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Yah sometime I just want to imagine how much faster the 0-60 would be if the off the line start weren't as slow, probably would shave off a fraction of a second off at least.
 
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