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Car Forum / BMW Cars / February 2005Octane for 3 Series
What are the pros and cons of using lower octane gasoline in a 2005 BMW 3 series? The book calls for 91 octane or higher, but 91 isn't made anymore, leaving 93 octane as the only option, according to BMW. Has anyone been using 89 or even 87 octane without any problem? And why not? Won't be a problem. The ECU should accommodate lower octane and roll back ignition advance as necessary to insure detonation does not occur. That'll cost you some power and mileage, perhaps making the 93 octane not such a bad choice. Oil companies imply that their higher octane fuel has better additive packages (Shell in particular in their recent ads), perhaps conducive to cleaner exhaust valves and injectors. > What are the pros and cons of using lower octane gasoline in a 2005 BMW 3 > series? The book calls for 91 octane or higher, but 91 isn't made anymore, > leaving 93 octane as the only option, according to BMW. Has anyone been > using 89 or even 87 octane without any problem? And why not? You should try and get Sunco they make 91 if there is any of those station in your area and it does make a difference to use a higher octane not only you get better performance but in the long run it will pay off. > What are the pros and cons of using lower octane gasoline in a 2005 BMW > 3 series? The book calls for 91 octane or higher, but 91 isn't made > anymore, leaving 93 octane as the only option, according to BMW. Has > anyone been using 89 or even 87 octane without any problem? And why not? I don't geddit. You're talking of an expensive modern car and you ask about using a fuel that is lower octane than recommended? As I don't want to make any assumptions I'll let you tell us why you are asking the question. DAS For direct contact replace nospam with schmetterling --- > What are the pros and cons of using lower octane gasoline in a 2005 BMW 3 > series? The book calls for 91 octane or higher, but 91 isn't made anymore, > leaving 93 octane as the only option, according to BMW. Has anyone been > using 89 or even 87 octane without any problem? And why not? I have been using the mid-grade for years. > What are the pros and cons of using lower octane gasoline in a 2005 BMW > 3 series? The book calls for 91 octane or higher, but 91 isn't made > anymore, leaving 93 octane as the only option, according to BMW. Has > anyone been using 89 or even 87 octane without any problem? And why not? >I have been using the mid-grade for years. That is what is recomended for all 3 of my BMWS (E36M50, E34M60, E36/7M52). AKI 89 or better. It's in the owners manual and on the gas caps. But we still see AKI 91 around here. Some stations have 91 and others have 93. If you really want to be anal about it you could pump half and half and get octane ratings in between. Heck, that's what they do at Sunoco stations at the pump. -Fred W > >I have been using the mid-grade for years. > > That is what is recomended for all 3 of my BMWS (E36M50, E34M60, > E36/7M52). > AKI 89 or better. It's in the owners manual and on the gas caps. I don't know about the gas caps, it isn't printed on mine nor is it printed on the inside of the fuel door. The Owner's Manual does say that 91 (RON) is the preferred fuel, but 89 will work fine, that is what I use. I have never tried 87. >> >I have been using the mid-grade for years. >> [quoted text clipped - 5 lines] > printed > on the inside of the fuel door. Strange. All 3 of mine are. Must be a locale thing... > The Owner's Manual does say that 91 (RON) is > the preferred fuel, but 89 will work fine, that is what I use. I > have never > tried 87. But Jeff, you live in California. Pumps in the US are not identified with RON. Other parts of the world use the RON number. RON is the Research Octane Number and is an artificially high number based on research parameters. The octane ratings we see are AKI (Anti Knock Index) also known as PON (Pump Octane Number), which is the average of RON and MON. The short of it is 89 AKI (mid grade in the US) is most likely at *least* 91 RON. Also, the use of the word "premium" in BMW owners manuals can be confusing as it means different things in different parts of the world. The best bet is to just make sure your fuel meet spec knowing the RON, MON, PON/AKI situation. Here's a good reference: http://www.btinternet.com/~madmole/Reference/RONMONPON.html -Fred W > of it is 89 AKI (mid grade in the US) is most likely at *least* 91 > RON. I did some research in this topic since I shipped my BMW to Europe couple of weeks ago and wanted to know what gas I should use there. According to specs provided by local refining companies, the lowest octane sold in that part of the Europe (95 RON) equals to 91 PON/AKI. So, there are local differences in octanes and probably also differences in user's manual localizations. BR:Z About which country are you talking? Your info applies to the the UK but not to Germany, for example, where lower grades are available. The fact remains that the vast majority of cars in Europe run on 95 octane -- thise that don't run on diesel, that is.... DAS For direct contact replace nospam with schmetterling --- [...] > I did some research in this topic since I shipped my BMW to Europe couple > of [quoted text clipped - 9 lines] > > BR:Z > About which country are you talking? Your info applies to the the UK but > not to Germany, for example, where lower grades are available. > > The fact remains that the vast majority of cars in Europe run on 95 > octane -- thise that don't run on diesel, that is.... Finland, that is. BR:Z > >> >I have been using the mid-grade for years. > >> [quoted text clipped - 7 lines] > > Strange. All 3 of mine are. Must be a locale thing... I am surprised this information is not on the inside of my fuel door or on the cap. But, it isn't for whatever the reason might be. > > The Owner's Manual does say that 91 (RON) is > > the preferred fuel, but 89 will work fine, that is what I use. I [quoted text clipped - 10 lines] > of it is 89 AKI (mid grade in the US) is most likely at *least* 91 > RON. You are correct, my pumps do not specify RON. Sorry for my confusion. The pumps are marked 87, 89, and 91. I use 89. > Also, the use of the word "premium" in BMW owners manuals can be > confusing as it means different things in different parts of the > world. The best bet is to just make sure your fuel meet spec knowing > the RON, MON, PON/AKI situation. Here's a good reference: > > http://www.btinternet.com/~madmole/Reference/RONMONPON.html I have only known Premium to mean the highest grade available. Depends on the area/country. Best to avoid adjectives altogether and use numbers. don't you think? DAS For direct contact replace nospam with schmetterling --- [...] > I have only known Premium to mean the highest grade available. My 318 ti Owner's Manual refers to AKI of 90. The AKI (anti-knock index) is the same as the Road Octane Index which is also known as the PON, or Pump Octane Number, both of which are the average of the Mon (Motor Octane test) and the Ron (Road Octane test). This is according to the following website: http://www.shell.ca/code/motoring/encyclopedia/info/jargon.html This is what it says: "RON, MON and Road Octane: "RON stands for a fuel's Research Octane Number. This value is measured under fairly easy test conditions. The MON, or Motor Octane Number, is a tougher test measured at higher engine speed and temperature. And the Road Octane Number - the octane number that relates most closely to actual driving conditions - is the average of these two values, i.e. Road Octane = (RON + MON)/2. The Road Octane Number is more frequently referred to simply as the octane number. Always be sure that the octane number a vendor advertises is its Road Octane value, not its RON. "Anti-Knock Index (AKI): "The same as the Road Octane Number. It is a numerical description of a fuel's ability to resist engine knocking. Anti-knock index is a more accurate description than octane number, which is why in the U.S. fuels are often given an anti-knock index instead of an octane number." So when my Owner's Manual calls for 90 AKI fuel, it is asking for 93 RON (+/-). Seems an 89 AKI would not involve much risk at all and it would save 10% on fuel price versus 93 AKI (premium). Any risks here other than loss of power and mileage? Not worth wrecking the engine to save on fuel expense! Fritz Wagner On Wed, 23 Feb 2005 11:26:49 -0800, "Jeff Strickland" <spamcatcher@yahoo.net> wrote: >> >I have been using the mid-grade for years. >> [quoted text clipped - 6 lines] >the preferred fuel, but 89 will work fine, that is what I use. I have never >tried 87. Columbus, Ohio > So when my Owner's Manual calls for 90 AKI fuel, it is asking for > 93 RON (+/-). Seems an 89 AKI would not involve much risk [quoted text clipped - 3 lines] > > Fritz Wagner The difference is usually 10 cents per gallon or about 5%, at least in these parts (Northeast USA). Also, many of the gas companies now have 93 AKI as you noted, so for that 5% increase you do get a significant increase in octane. That said, if you don't *need* the increased octane, it will be money wasted. Best bet is to run a few tanks of each fuel and carefully log conmsumption and performance then decide. -Fred W |
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