[DTM]

In US models, the handbook recommends premium, 91 octane gas.

However, all modern engines, such as BMW engines, have knock sensors, eliminating the danger of using a lower octane.

http://www.caranddriver.com/article....rticle_id=3604

I've read other articles like this and thought, when your not racing anybody, is it safe on an E90 to use a lower octane?

If people could tell me what octane they use, and whether they experience knock or other engine problems, it would be very helpful in my decision on buying an E90.

[0700700]

100 octane.... back home .. and 102 octane enriched when i go to turkey, only place ive ever seen that sells it

[JamieA]

I always use 98RON. I did put 91RON in accidentally once

[NaTuReB0Y]

91 octane is the highest we have here.........use to be 92....

California clean air law suck balls............

[DTM]

Originally Posted by NaTuReB0Y

91 octane is the highest we have here.........use to be 92....

California clean air law suck balls............

I think it's the same in the whole US. We only get 91 in Massachusetts as well.

[JamieA]

In another thread, it was explained to me that there are about 3 different methods for measuring octane levels. Research Octane Number or RON is what we use here and is also used in Eurpoe, but the US has a different system - PON or Pump Octane Number. The other system is MON - Motor Octane Number.

From memory, 98RON is equivalent to 95PON. 98RON which is what our engines are designed for.

The higher the octane level the cleaner the petrol, since that is what octane measures - purity. If anything the US laws should be encouraging use of higher octane fuels.

Here is a post from E90Fleet on what higher octane fuel does

Here is a site explaining RON, MON and PON

[ward]

if you cheap out on gas you shouldn't be driving a BMW

[Enroutte]

Originally Posted by ward

if you cheap out on gas you shouldn't be driving a BMW

i know! i agree.

i dont care how much gas i waste.. im more concerned about my mileage. i know, i'm anal. all my friends always complain about how much it costs to drive and im like, EH its just gas. its the inevitable! but but i hatee driving far because i dontlike high mileage onmy car.im weirddd, i know.

[shimshimhada]

Originally Posted by DTM

I think it's the same in the whole US. We only get 91 in Massachusetts as well.

93 AKI here in VA.

[visor]

Originally Posted by ward

if you cheap out on gas you shouldn't be driving a BMW

Agreed. Get the Accord V6 instead, it can get 244 hp from a 3L engine running on regular gas.

And as discussed in previous threads on this topic, the dollar savings in getting lower octane gas is negated by the poorer fuel economy. Not only that, you'll suffer some power loss as the knock sensors retard the timing to accomodate.

[Barry626]

Originally Posted by ward

if you cheap out on gas you shouldn't be driving a BMW

[thrill30]

I've been using 93 RON. However, I switched to 95 RON from last week.... I plan to stick with 95 RON until higher octane is introduced at our pumps.

[JamieA]

Originally Posted by ward

if you cheap out on gas you shouldn't be driving a BMW

I agree with you 100% ward.

[David328M-Sport]

98ron. tried 100ron but i felt that 98 is in fact better probably as our cars are primed for 98ron.

[David328M-Sport]

Originally Posted by JamieA

I always use 98RON. I did put 91RON in accidentally once

a whole tankful or just a bit till you realised what you were doing?

what was the performance difference?

[David328M-Sport]

Originally Posted by ward

if you cheap out on gas you shouldn't be driving a BMW

or any other quality motor car. thanks ward.
well said.

[espo]

Originally Posted by shimshimhada

93 AKI here in VA.

Same here is Buffalo.. (not sure about NYC). There are even a couple of Sunnaco's that have 94.

[ben1364]

This "octane" thread seems to pop up evert two or three weeks. Suffice it to say that uncle Charlie's friend's cousin from Burbank via Memphis doesn't know better than the BMW designers what fuel grade works beest in BMW engines. When all else fails, read the owners' manual.

[Atty]

93 RON

I still don't understand why people think they are somehow cheating the system by going with cheaper gas. The difference between 89 and 93 octane only amounts to about $2 per week on average, the cost of a regular Pepsi at a restaurant. So you just shelled out $35, $40, $45k on a new Bimmer and you are worried about shaving $100 or so a year off your bills. Gimme a break.

BTW, whether or not damage could occur depends on the engine and the manufacturer. It also depends on how often you go with the cheap fuel. In the short term (ie: maybe 1-2 years) you won't notice any extra wear to your engine. As previously mentioned, there will be no wear on a high performance engine with engine management controls that prevent early detonation when using low grade gas.

The damage occurs in the long-term, so it would only appear after the engine is older. If you don't plan to keep your car long-term, low grade gas won't affect your cheap self and you can use that saved money to buy 1 extra dinner or maybe a new shirt from the Gap each year. But the next owner of your car may start to experience the negative effects of the low grade gas.

[espo]

There have been so many threads about this that it's not funny... Do a search first.

That being said, the money you save using a lower grade fuel will be made up by the fact that you will get worse gas mileage since the engine has to "detune" itself to keep from knocking. Lets say that premium cost $.30 more a gallon than regular (usual spread) ($2.55 vs. $2.25). Lets also assume you get 3 MPG less on regular (I have seen this number quoted somewhere, just don't remember) taking the car from an average 25 MPG to 22 MPG, then you are spending EXACTLY the same $0.102 per mile on fuel.

Easiest way to put it is if you sent $40K on a car, put in it what the car manufacture recommends, there is a reason for it!!!!!

[Synikal]

Used to filler her up with Sunoco 94. Now 91 damn AZ!

[ACZakka325i]

i use 91 octane