[motorsport_cat]

Hi everyone, it's been a while since I posted...
So my mother just got a F30 328i MY 2013 and they told her she can use 87 octane, although near the fuel "hole" it says minimum 89 octane. She uses the 87 and the engine makes a rattling sound. Will it disappear if she uses 89, and is it better to use it?
Thank you all!

[Austinformedude]

Been discussed at length. Don't put crap fuel in your $45k turbo charged BMW. Spend a few extra Dollars and stick with premium fuel. This is a prime example of why I don't buy used cars.

[adhrp]

Originally Posted by Austinformedude

Been discussed at length. Don't put crap fuel in your $45k turbo charged BMW. Spend a few extra Dollars and stick with premium fuel.

^^^ exactly. Search on the topic and you'll find a dozen threads on it. But in short, DO NOT use 87. Use 91 as much as possible. If she really cannot find 91 then 89 is alright.

[f30kid]

93 is ok too isnt it?

[Tony_YYZ]

Originally Posted by f30kid

93 is ok too isnt it?

Yes, but it's not necessary and you're just wasting money really. Unless 91 is not available and 93 is the next closest option without going under.

[BeachsideF30]

At all of my pumps I have 87-89-93. No 91, so I just use 93 idc a cpl dollars isnt going to put me in the red

[tallshortguy]

I hope it wasn't a dealer who told her this as that's some sad lack of knowledge. The fuel cap as you mentioned and the manual both say 89 is minimum with 91 recommended.

[philbake]

Don't use less than 89 in the Turbo 4. It's designed to deliver peak efficiency with 91. You're probably spending more on fuel if you go below that anyway, so not saving anything. In the older NA inline 6, you can use regular, or mid grade, but I wouldn't do that with the turbo. Here in Denver at altitude, the BMW dealer told me they use mid grade (87 here) on all their cars and there's no difference. Here, you get 85/87/91.

[motorsport_cat]

Originally Posted by philbake

Don't use less than 89 in the Turbo 4. It's designed to deliver peak efficiency with 91. You're probably spending more on fuel if you go below that anyway, so not saving anything. In the older NA inline 6, you can use regular, or mid grade, but I wouldn't do that with the turbo. Here in Denver at altitude, the BMW dealer told me they use mid grade (87 here) on all their cars and there's no difference. Here, you get 85/87/91.

Why would it be fine to use 87 in Denver?

[Austinformedude]

Originally Posted by motorsport_cat

Why would it be fine to use 87 in Denver.

Denver is a mile above sea level and has thinner air that is less dense. This has a dramatic effect on ICE motors because they get less of an air charge. Turbos are much less prone to power loss at altitude, however, because they can compress even more air into the cylinder. Many cars know the barometric pressure and will adjust to compensate as well. Still, I am going to advise against going with 87 octane because these are high compression motors prone to predetonation (knock) that is VERY hard on the motor. Predetonation doesn't go away at altitude. This myth works with older engines because they would no knock at high altitudes because they suffered such power loss in the first place they were getting fuel cuts way before they had enough fuel to cause a predet condition.

[Kafkaesque328]

The inside of my cap says 91.

Use 91 or better and try to come to terms with the hardship of paying $2 more to fill the tank in her premium $45k automobile.

[motorsport_cat]

Originally Posted by Kafkaesque320

The inside of my cap says 91.

Use 91 or better and try to come to terms with the hardship of paying $2 more to fill up the tank in your premium $45k car.

Her cap says 89. I wonder why!

[philbake]

Originally Posted by Austinformedude

Denver is a mile above sea level and has thinner air that is less dense. This has a dramatic effect on ICE motors because they get less of an air charge. Turbos are much less prone to power loss at altitude, however, because they can compress even more air into the cylinder. Many cars know the barometric pressure and will adjust to compensate as well. Still, I am going to advise against going with 87 octane because these are high compression motors prone to predetonation (knock) that is VERY hard on the motor. Predetonation doesn't go away at altitude. This myth works with older engines because they would no knock at high altitudes because they suffered such power loss in the first place they were getting fuel cuts way before they had enough fuel to cause a predet condition.

I use 91 here in Denver in my 328i F30. My wife has a 2010 X3 (N52 non Turbo 6) and having run both 91 and 87 find I can run mid grade in that puppy (which is 87 here at altitude) and cannot tell any difference, power or efficiency-wise). The x3 loses more power at altitude. In fact, I live at 6,000 ft. I've never taken my 328ix to sea level, but I can tell you that it's much more powerful up here than the X3, which feels a little sluggish whether I use 87 or 91. (Keep in mind up here that 87 is mid grade. 85 is regular and 91 is the highest available.

[motorsport_cat]

Couldn't search this before posting, I'm on mobile

[stormlv]

Originally Posted by Kafkaesque320

The inside of my cap says 91.

Use 91 or better and try to come to terms with the hardship of paying $2 more to fill the tank in her premium $45k automobile.

The intake of my 320xi loaner says AKI 91 (95 RON) as well.
Then again, we don't have anything lower than that here

[adhrp]

Originally Posted by BeachsideF30

At all of my pumps I have 87-89-93. No 91, so I just use 93 idc a cpl dollars isnt going to put me in the red

Yeah, in that case I'd go with 93. Where I live (high altitude), 91 is the highest so I mentioned 91.

[kent11202]

Mine says 91 here in CA - why would anyone use a lower octane to save a few pennies? Sheesh.

[Leo bimmer]

Lowest octane fuel here is 95 we never had any problems with fuel