[nakamuru]

So i was told that my 30i requires premium 92 or above and i been doing that but that past three or four times been doing regular by accident . Previous car i always did regular which 87. How much damage do you think i did or am i safe as its only been done 3 to 4 refills. Never understood octane etc

[zeich83]

Modern engines have knock sensors which can sense the offset in ignition timing due to the lower octane fuel which will prevent engine damage. They will adjust and it will limit your power output. For just cruising lower octane is generally fine, but when you floor it and the pressures get high it is not great for the engine.

Just stick to premium from now on and you'll be fine.

[foglem]

Octane determines how much pressure will cause the gas/air mix to “detonate” or literally explode. Needless to say that happening before the engine is ready is a bad thing. Higher octane can take a higher pressure as its “less” explosive. This also sadly means there is a lower energy density in higher octane gas (you’re paying more for less). As mentioned the modern engines try to safeguard themselves against this. Turbocharged engines typically always need high octane because they boost the pressure beyond normal compression anyway. More than likely your car is performing under its expected level and this is why as the engine has detuned itself to protect itself.

[calintexas]

The salient fuel advice for the M40i follow. You should look at the Driver's Guide for your car. I'm going to guess that they'll be identical:

[nakamuru]

Originally Posted by zeich83

Modern engines have knock sensors which can sense the offset in ignition timing due to the lower octane fuel which will prevent engine damage. They will adjust and it will limit your power output. For just cruising lower octane is generally fine, but when you floor it and the pressures get high it is not great for the engine.

Just stick to premium from now on and you'll be fine.

Yikes so i seem to floor it a lot. Changing back to 92 octane costco i should be ok right? No warning light etc.

[DTRJ]

Originally Posted by nakamuru

Yikes so i seem to floor it a lot. Changing back to 92 octane costco i should be ok right? No warning light etc.

Yes, and Costco is a Top Tier fuel!

[chassis]

German automakers are based in a land where 95 octane is the norm, hence a contributing factor to the octane recommendation in non-German markets. Use the recommended fuel to achieve performance near what the manufacturer warrants.

[clivem2]

Beware the difference between octane ratings between US and Europe. US 93 is 98 in Europe. US 91 is 95 in Europe.

[Juris]

BMW recommends 91 and, for a minimum, 89. I am comfortable relying on a BMW engineering recommended range of 91-89.

[kevinkay]

My previous X5 2004 was traded in with 215 thousand miles and still as strong and sweet sounding as new - I only used "regular" from day 1.

I am not going to argue that the car would have "preformed" better with higher octane, but it definitely, positively did no damage

[DTRJ]

Originally Posted by kevinkay

My previous X5 2004 was traded in with 215 thousand miles and still as strong and sweet sounding as new - I only used "regular" from day 1.

I am not going to argue that the car would have "preformed" better with higher octane, but it definitely, positively did no damage

Your gas mileage would be a lot better if you used the recommended fuel. Todays computer controlled engines will usually prevent engine damage, however they retard the spark and engine timing which will reduce your mileage per gallon

[JDsX3]

To my knowledge, most Costco Premium gas is rated 91 and is top tier. It is perfect for our BMW X3s (and have also used it for years in my Corvette, which also requires Premium).

[MrGlass]

From Costco’s website:

Regular unleaded and ​p​remium unleaded ​gasoline, and ​d​iesel at select locations. Gasoline ​octane can vary by state, but at Costco, it's typically 87 octane for Regular Unleaded and 91 octane for Premium Unleaded Gasoline.

In Northern Virginia, it’s 93 octane. For what it’s worth, premium is typically 60-70 cents less expansive than other stations.

[KAP8]

I only use Shell Vpower 93 in our BMW's. That is what BMW recommends, so that is what I use.

[nakamuru]

Originally Posted by kevinkay

My previous X5 2004 was traded in with 215 thousand miles and still as strong and sweet sounding as new - I only used "regular" from day 1.

I am not going to argue that the car would have "preformed" better with higher octane, but it definitely, positively did no damage

Im all for car longevity so during the 215 k what issues did you run into or? Any accidents? I wanna keep mine long too

[DTRJ]

Originally Posted by KAP8

I only use Shell Vpower 93 in our BMW's. That is what BMW recommends, so that is what I use.

As far as I know BMW does not recommend any specific fuel any longer. They used to recommend BP, but now I believe they recommend any TOP TIER fuel, which is most of the big companies such as Shell, BP/Amoco, Mobil/Exxon, Valero, Costco and many others on the Top Tier website. They do not include Bj's. I have been using BP 93 for over 10 years with no issues in any of my BMW's. Just recently switched to Shell 93 because where I am it's about 10 cents a gallon less than the BP 93

[KAP8]

BMW very much recommends Shell. It says so on our M40i on the fuel filler door.

[Aaaaaaaaa]

Yea engine is toast. Just sell it.

[DTRJ]

Originally Posted by KAP8

BMW very much recommends Shell. It says so on our M40i on the fuel filler door.

I don't have my X4M40I yet, but expect it in November. My 2011 or 2014 335 had in the owners manual BMW recommends BP fuels. I guess who pays the most gets the BMW endorsement.

[Bob in IL]

Originally Posted by DTRJ

I don't have my X4M40I yet, but expect it in November. My 2011 or 2014 335 had in the owners manual BMW recommends BP fuels. I guess who pays the most gets the BMW endorsement.

Yeah, the big brands spend a lot on marketing Shell seems to do the best all around job

[KAP8]

Originally Posted by DTRJ

I don't have my X4M40I yet, but expect it in November. My 2011 or 2014 335 had in the owners manual BMW recommends BP fuels. I guess who pays the most gets the BMW endorsement.

My 2015 435i doesn't recommend Shell either, just premium fuel. They switched to a deal with Shell sometime after that. But I've been using Shell in my BMW's since 2008. Mike Miller has always preached about using Shell Vpower, so I do.

[Alias1431]

Originally Posted by kevinkay

My previous X5 2004 was traded in with 215 thousand miles and still as strong and sweet sounding as new - I only used "regular" from day 1.

I am not going to argue that the car would have "preformed" better with higher octane, but it definitely, positively did no damage

Tell me your longevity secrets.