BMW 328i filled with regular unleaded

So, I got my shiny new bike recently. Then, my wife started talking about getting a used BMW car. Long story short, I caved and she got her BMW. The car ran great until she accidentally put in regular unleaded instead of premium. Shortly thereafter she got a cylinder misfire engine code. After checking around on BMW car forums, it seems BMWs can be quite sensitive to low octane gas and it isn't uncommon to get a check engine light if premium isn't used. Her tank is 3/4 full right now.

Now my question. Would the best way to raise the octane be to put in 1/4 tank of 110 octane racing gas, or to us an octane booster? If an octane booster is the way to go, what brand?

Thanks!!

Royal Purple Max Octane Booster!

http://www.motoiq.com/MagazineArticl...e-Booster.aspx

Most octane boosters are snake oil and will only raise octane tenths of a point if any! Nothing magical can be had from a can, depending on tank size etc. will dictate your dilution percentage on any product used.

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Originally Posted by Fla_rider

Royal Purple Max Octane Booster!

http://www.motoiq.com/MagazineArticl...e-Booster.aspx

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Thanks! It looks like the auto parts store near us carries it. There's one thing I almost forgot about. When my wife brought the car to AutoZone to have the check engine light read, the guy told her to dump in a can of Seaform. So, she put dumped a can of Seafoam into the tank. It seems idiotic as I don't think Seafoam makes any claims about boosting octane. Would it be okay to add the Royal Purple even though the Seafoam is already in there? I'm concerned too many additives might mess something up.

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Originally Posted by jkelley

Most octane boosters are snake oil and will only raise octane tenths of a point if any! Nothing magical can be had from a can, depending on tank size etc. will dictate your dilution percentage on any product used.

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So, your opinion would be to use the racing fuel to raise the octane?

+1 on air plane fuel or what ever the label is...SeaFoam will not hurt...may help as well..... I am not real sure the problems fuel/low octane....seems to me that a lot of vehicles call for hi fuel...but doubt you would be left on the sides of the road if no hi/oct was available....JMHO

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Originally Posted by CheesyRider

So, I got my shiny new bike recently. Then, my wife started talking about getting a used BMW car. Long story short, I caved and she got her BMW. The car ran great until she accidentally put in regular unleaded instead of premium. Shortly thereafter she got a cylinder misfire engine code. After checking around on BMW car forums, it seems BMWs can be quite sensitive to low octane gas and it isn't uncommon to get a check engine light if premium isn't used. Her tank is 3/4 full right now.



Now my question. Would the best way to raise the octane be to put in 1/4 tank of 110 octane racing gas, or to us an octane booster? If an octane booster is the way to go, what brand?

Thanks!!

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Top off the tank with premium and before you do dump a bottle of 108 octane booster. Seafoam is a tune up in a bottle but I prefer star tron. Best of luck to you.

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Originally Posted by Steve 0080

+1 on air plane fuel or what ever the label is...

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Careful on that. Av gas is 130 octane, fortified with lead AFAIK.
You do not want tetraethyl lead poisoning the cat converter and O2 sensors.

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Originally Posted by CheesyRider

So, your opinion would be to use the racing fuel to raise the octane?

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Personally I would ride it out to below 1/4 tank and then put 93 in it, but if you are so inclined to use racing fuel knowing the tank size you could probably get pretty close to the proper mix.?.?

Thanks for the advice everyone. My wife just called from the gas station. She was going to put the 110 octane in the tank, but the nozzle was too big. Instead, she topped off with non-ethanol premium.

It just occurred to me that if the check engine light comes back on, I can siphon the gas and put it in my van. Then I can fill her tank completely with premium fuel. Luckily, the car is under warranty. So, if it turns out it was a just a coincidence that the check engine light came on with regular unleaded fuel, we shouldn't have to pay for a repair.

This guy is the Stephen Hawking of fuel, easy to talk to.

http://bndautomotive.com/

Some additional clarification - a modern car ( incl. your BMW ) with a high-octane fuel requirement can be safely run on lower-octane gasoline. Modern vehicles are equipped with a knock sensor, which will automatically detect knock events and then retard ignition timing to prevent knock. It will result in slightly less engine power, but unless you spend a lot of time driving around at full-throttle, the odds are you won't notice any difference at all. It won't hurt anything, either. The engine is designed to be able to safely run on low-octane gasoline for extended periods of time.

The "warning light" is not related to the difference of octane number . Most likely it's effect of computer read-out of any other malfunction , which came in time of re-fueling the gas . You need to diagnose your car in reputable shop .

:icon_cool:

How many miles on that 2.8 liter 6 cylinder BMW ? What year ?

My last BMW was a 540I and I fueled it with 87 Octane every time even though it called for 92, it ran perfectly fine.

When I hit 140,000 miles the Check engine light came on. The local Auto parts store re-set it for me but it came back on 3,000 miles later. We traced it to a oxygen sensor.

My car had 2 so I replaced both at the same time and the light went away.

Sold that car with 150,000 miles. That V8 was the Ultimate driving machine.

I now drive a V6 and it's not the same.:icon_frown:

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Originally Posted by Limoles

The "warning light" is not related to the difference of octane number.

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The more I research, the more I'm inclined to believe you are correct. The check engine light most likely had nothing to do with the octane and was just coincidence. I guess if the code comes back after a full tank of premium, I'll know for sure.

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Originally Posted by Phantom

How many miles on that 2.8 liter 6 cylinder BMW ? What year ?

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It's a 2009 with about 46,000 miles. It's actually a 3.0 liter. I have no idea why it's a 228 and not a 330.
Although I think my wife was somewhat crazy to get rid of her newer lower miles car, I must admit that I love driving her car. It has all-wheel-drive and a manual transmission for extra fun!

http://s16.postimg.org/f4lpcmcut/bmw.jpg

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Originally Posted by CheesyRider

The more I research, the more I'm inclined to believe you are correct. The check engine light most likely had nothing to do with the octane and was just coincidence. I guess if the code comes back after a full tank of premium, I'll know for sure.



It's a 2009 with about 46,000 miles. It's actually a 3.0 liter. I have no idea why it's a 228 and not a 330.
Although I think my wife was somewhat crazy to get rid of her newer lower miles car, I must admit that I love driving her car. It has all-wheel-drive and a manual transmission for extra fun!

http://s16.postimg.org/f4lpcmcut/bmw.jpg

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Phantom's suggestion and my suspicions ( based on experience with BMWs ) , most likely is related to one of 2 oxygen sensors.
If diagnose will pin point failure of only one , I would replace 2 of them anyway . It's very common problem and shouldn't be consider as a deterioration of the car . It's following poor quality of gas at all . Some gas stations with older underground tanks contains water and sluggish elements , which eventually getting into consumers cars with unwanted staff . Age and high mileage could be an another factor , but in 5-6 years old car is not a case . I hope , it is the only problem and can be solved within simple diagnose and relativaly easy replacement . Buy ONLY designated Bosch Premium O2 sensor . Good luck .

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Originally Posted by Limoles

Some additional clarification - a modern car ( incl. your BMW ) with a high-octane fuel requirement can be safely run on lower-octane gasoline. Modern vehicles are equipped with a knock sensor, which will automatically detect knock events and then retard ignition timing to prevent knock. It will result in slightly less engine power, but unless you spend a lot of time driving around at full-throttle, the odds are you won't notice any difference at all. It won't hurt anything, either. The engine is designed to be able to safely run on low-octane gasoline for extended periods of time.

The "warning light" is not related to the difference of octane number . Most likely it's effect of computer read-out of any other malfunction , which came in time of re-fueling the gas . You need to diagnose your car in reputable shop .

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You have single-handedly restored my belief that intelligent life resides in New Jersey, you are the man. I have never used high test in any of my cars or bikes. You have no choice on the water, it's all hi-test here.

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Originally Posted by taxfree4

You have single-handedly restored my belief that intelligent life resides in New Jersey, you are the man. I have never used high test in any of my cars or bikes. You have no choice on the water, it's all hi-test here.

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This is proving again , that all cars being on the roads in USA are the best among best in the world and all of them can take
(technically speaking) huge ABUSE . Yes - we might understand now , why our gas is cheaper then that in Europe . If I tell
you , that "worst" petrol grade sold in Europe has 92 octanes ( and going up to 99 ), it will clarify the question : "Why is so" ?
Well - OCTANES contain structural isomers (stereoisomers) , which are costly in production and consumers must pay for it .
Octane boosters are required for immediate response in "stop and go" habits in smaller european cities or even highways .
Americans driving cars with much more powerful engines and traditionally , most of them are overbuild and do not need any
enhancements on longer distances ( which we are famous of ) . So , re-assuming this , using hi-octain gasoline is the only
factory recommendation in hi-performance cars and thanks to self-adjusting sensors , we can use lower petrol grades without
sacrificing pleasures of driving them . However , there is another factor related to temperatures and time of fuel burn-out
in combustion chambers , which definitely increases performing responsiveness in racing cars or motorcycles , that's why
these vehicles needs much higher quality of gas .

That's a nice looking car. I always loved bmw's but scared to buy one cause of maintenance costs (so I've been told). I would run that cheap gas out or try to siphon it out. I'm a firm believer if the car calls for premium then that's what it needs to run and perform how it was built to do. Kinda ironic the problems didn't start until it was filled with 87 octane. goodluck and I hope it all works out

Before you go too far on additves or anything(all of which may be good suggestions) a question
When she put gas in it did she tighten the gas cap and make it click a couple of times?
Dont know BMWs but most American cars go to the shop with a check engine light and all it is -is the gas cap is not on tight. Causes a vacuum leak and there's your check engine light. If you haven't checked,take the cap off,then put it back, making sure it clicks a couple of times.
Sounds silly but check it out..

I should have updated this thread when the problem was resolved. The misfire was just a coincidence and had nothing to do with the gasoline grade. A coil was bad. It has been replaced and the car has been running great. Thanks everyone!

Where am I... what year is this... why didn't the guy at the auto store put a scanner on it and read the code?? Problem indicated... solution imminent. I guess he really wanted to sell that Seafoam :icon_biggrin:

Octane ratings are calculated differently in different parts of the world, so 92 or 99 in Europe may not coincide with the same numbers here, yes?

Octane boosters do work... they are not snakeoil. Torco or Lucas are the most popular brands.

Cars that call for premium gas, should get premium gas. Sure the knock sensors will pull 5 to 20 degrees of timing and keep things putting along... but that's because... your engine is DETONATING from the lower octane.