[jcl89]

After a long day of work I wasn't paying close attention at Chevron, filled half tank with 87. Drove the car home (21 mi) in Eco Pro mode.

I'm guessing the car has knock sensors, so I figured I should be OK - just stay off the boost and then fill back up with 91 when it's quarter tank?

[snaketh]

Originally Posted by jcl89

After a long day of work I wasn't paying close attention at Chevron, filled half tank with 87. Drove the car home (21 mi) in Eco Pro mode.

I'm guessing the car has knock sensors, so I figured I should be OK - just stay off the boost and then fill back up with 91 when it's quarter tank?

Yes the knock sensor will pull the timing and your engine will be fine. If it were me I'd either buy some octane booster from the store or I'd drive carefully. The fact it's only half the tank makes it even less of a worry.

[seedyrom]

On the plus side ... think of the mods you can get done with those sweet savings

[3rdcoast228i]

I believe my 228i manual said you can use 89 octane if you can't get 91 for some reason. So if you mixed 87 with 91 it should be close to 89

I would just keep topping the tank off with 91 after you get done driving for the day.

[marcthedark]

a) as you said keep a light right foot
b) a bottle of octane booster (mostly ease of mind)
c) add 91 when you need and don't worry about it

[BEM-S4]

Maybe I'm nuts but I have these stickers in all my tuned cars. We venture into NJ occasionally where it's full service only. Good reminder in any event.

[chattanooga240]

Have not owned a car that used anything lower than 91 in over 15 years. I could not mistakenly grab the wrong pump if my life depended on it.

Not to worry OP, no damage done, just try not to make a habit out of it.

[USA-RET]

Originally Posted by jcl89

After a long day of work I wasn't paying close attention at Chevron, filled half tank with 87. Drove the car home (21 mi) in Eco Pro mode.

I'm guessing the car has knock sensors, so I figured I should be OK - just stay off the boost and then fill back up with 91 when it's quarter tank?

Yep. You should be @ 89 octane even w/ your mistake. My dealer told me it's okay to run mid-grade in the car, but mine has seen nothing less than 93 octane since owing. Plenty of debate among owners that opt for the 89 vs the 91 w/ no ill effects reported.

So, yes, I'd stay off the gas pedal until you burn the gas in the tank and fill w/ the high octane at each fill up or stop at your local auto parts store and dump a bottle of octane boost in the tank (which is what I'd probably do).

[MadOzodi]

Originally Posted by BEM-S4

Maybe I'm nuts but I have these stickers in all my tuned cars. We venture into NJ occasionally where it's full service only. Good reminder in any event.

Yanno, I noticed the lack of any "Premium Fuel Only" reminders around my fuel fill port/door...now I'm all paranoid.

jcl89, think of it this way...at least you didn't fill a diesel fuel tank with gasoline, right?

[crabu2]

I never understood why there's such a fuss over this.

Tuners pull timing when the engine knocks, but no one seems to think twice about running a tune. Why do people feel their engine will go pop because they ran a lower octane than what's recommended or required for advertised power output?

Some companies now advertise different power ratings based on the octane used...

BTW, I was watching the hp/tq numbers built into iDrive and notice most times, I'm cruising with less than 40hp. The only time I was jumping over 100hp was when I was passing or merging onto the highway.

[NVHoo]

Originally Posted by USA-RET

Yep. You should be @ 89 octane even w/ your mistake. My dealer told me it's okay to run mid-grade in the car, but mine has seen nothing less than 93 octane since owing. Plenty of debate among owners that opt for the 89 vs the 91 w/ no ill effects reported..

There is some regulatory reason why CA refineries are limited to 91 and CA supplies most of the SW. So 91 is the best you can buy unless you go for racing fuel. Then there are some high altitude refineries in the Rockies that sell 85 octane as "regular" because of the thin air.

[doublevanosrc]

Originally Posted by seedyrom

On the plus side ... think of the mods you can get done with those sweet savings

[bryan_G01]

Add a can of octane boost ftw

[3.0L]

Originally Posted by jcl89

After a long day of work I wasn't paying close attention at Chevron, filled half tank with 87. Drove the car home (21 mi) in Eco Pro mode.

I'm guessing the car has knock sensors, so I figured I should be OK - just stay off the boost and then fill back up with 91 when it's quarter tank?

Oh man, now you did it. Just sell it.

[jcl89]

I found a 93 octane place within a reasonable distance - I'll let it get down to half tank, fill with 93, then figure I'll be at 91 since I'm running about 89 right now with the combination.

[B_Rice]

It won't destroy your car or anything. You'll just have slightly worse performance and mpg for a until you fill it up again.

[TajoMan]

knock sensor will retard the ignition timing if it gets to that point.
Typically knock can be an issue when the engine is loaded and weather (intake air) is hot.
So, as long as you are not running on the track, you should be fine.
For sure, you will not have full 320 hp with 87 octane and that's it.

[Deutsche-Broke]

Just my .02, but please stop with the octane booster garbage.. It's no better than chiropractic and a great way for oil companies to sell more garbage off the cracking tower instead of feeding it to our cattle and selling STP oil treatment to the, "Lawrence Welk" crowd..

My question is, why would the EPA be tightening emission standards and regulations exponentially to the point where BMW has to re-tool to make suitable power from 4 cylinders just to meet future standards and then defeat everything by letting a bottle of, "magic octane extreme hyperspace boost juicz" sit on the shelf of your local Pep Boys?

Doesn't make a lot of sense to leave a massive loophole like that..

Ever hear of a OEM recommending or noting that any "octane booster" is suitable for their product? Probably not since the mid 80's with leaded gas before it was phased out...

Again, not claiming to know everything here but our engines are designed to run on all, "domestic", pump gas. 91 to 93 is "recommended" but If it's 87, it will probably be a few hp off because of adjusted engine timing, but you probably couldn't notice unless it was under strict testing procedures and heavy load.

That being said.. I wouldn't suggest trying diesel unless you have the little "d". on the trunk..

[snaketh]

Originally Posted by Deutsche-Broke

Just my .02, but please stop with the octane booster garbage.. It's no better than chiropractic and a great way for oil companies to sell more garbage off the cracking tower instead of feeding it to our cattle and selling STP oil treatment to the, "Lawrence Welk" crowd..

My question is, why would the EPA be tightening emission standards and regulations exponentially to the point where BMW has to re-tool to make suitable power from 4 cylinders just to meet future standards and then defeat everything by letting a bottle of, "magic octane extreme hyperspace boost juicz" sit on the shelf of your local Pep Boys?

Doesn't make a lot of sense to leave a massive loophole like that..

Ever hear of a OEM recommending or noting that any "octane booster" is suitable for their product? Probably not since the mid 80's with leaded gas before it was phased out...

Again, not claiming to know everything here but our engines are designed to run on all, "domestic", pump gas. 91 to 93 is "recommended" but If it's 87, it will probably be a few hp off because of adjusted engine timing, but you probably couldn't notice unless it was under strict testing procedures and heavy load.

That being said.. I wouldn't suggest trying diesel unless you have the little "d". on the trunk..

You're wrong. High quality octane boosters are not like chiro's. They do work.

A quality booster contains MMT(Methylcyclopentadienyl manganese tricarbonyl) which is what refineries use to raise the octane of their fuels. NF Octane Booster Racing Formula is a decent brand that has been shown to increase RON by 2.8 points. Much cheaper to buy the right gas of course.

[Deutsche-Broke]

Originally Posted by snaketh

You're wrong. High quality octane boosters are not like chiro's. They do work.

A quality booster contains MMT(Methylcyclopentadienyl manganese tricarbonyl) which is what refineries use to raise the octane of their fuels. NF Octane Booster Racing Formula is a decent brand that has been shown to increase RON by 2.8 points. Much cheaper to buy the right gas of course.

You are correct... I stand corrected with one caveat.. The EPA doesn't register it as an allowed additive.. It is not for sale off the shelf in the US.. (At least that I can find in 20 minutes online, but that doesn't mean you couldn't smuggle it in via mail, etc..)

It makes perfect sense that it is available in the UK and AU as the EPA regs do not exist.

And your last point is the best of course..

[Rayscott]

Originally Posted by snaketh

You're wrong. High quality octane boosters are not like chiro's. They do work.

A quality booster contains MMT(Methylcyclopentadienyl manganese tricarbonyl) which is what refineries use to raise the octane of their fuels. NF Octane Booster Racing Formula is a decent brand that has been shown to increase RON by 2.8 points. Much cheaper to buy the right gas of course.

And, I have a chiro who does wonders for my sometimes sore back. Been using him for years. Better than surgery. Get your facts right before making a statement.

[Gladius]

It's hard to find 93 octane here in Colorado. Most premium here is 91.