I mistakenly put 87 octne fuel in my tank for my BMW 325ci - I usually put 93 octane in it. Will this damage my engine - the tank was .25 full before I put in the lower octane gas.
No worries. It will do no harm.
David is right 1 tank shouldn't be a problem but if you are worried just put in some good octane booster.
no harm done - just don't make a habit of it or your engine will start pinging....
Your engine will start pinging as soon as the high octane in the lines is burned off, which won't be long. You will also find that the computer retards the timing to stop this, and the timing will retard so far that the car will barely run, will have little power and will burn gas like a road warrior. Add octane boost now, and then at the 3/4 tank mark, top up with the super-high, 94 octane, or what ever the highest is you can get. Do that for a couple of times, and then go back to your normal grade of fuel. At the price of a replacement engine, it is better to take no chances on causing damage.
Cheap fuel wont hurt it at all poor performance is all and crappy mileage
Looking for a Used 3 Series in your area?
CarGurus has 38,830 nationwide 3 Series listings starting at $1,498.
Search BMW 3 Series Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
BMW 3 Series Experts