Jamex316 1 Report post Posted March 21, 2011 Got my first bmw e39 530i a few weeks back, first tried 91 octane. Computer shows a fuel consumption of 7km/l of petrol, also making funny sounds... Just fuelled up with shell vpower 95 octane fuel, immediately the fuel consumption improved to 9.8km/l of petrol!!! Wow, what a difference... Quote Share this post Link to post Share on other sites
Michael. 2312 Report post Posted March 21, 2011 Not surprising, they were designed to run with a higher octane. Quote Share this post Link to post Share on other sites
huff3r 347 Report post Posted March 21, 2011 Lucky it was a fairly modern engine with a reasonably smart computer, else you could've been looking at some pricy bills for a new engine there... Quote Share this post Link to post Share on other sites
Jamex316 1 Report post Posted March 21, 2011 Surely its not as bad as using diesel in it.... Quote Share this post Link to post Share on other sites
pjay 8 Report post Posted March 21, 2011 Surely its not as bad as using diesel in it.... Only use diesel if you have insects installed. Quote Share this post Link to post Share on other sites
huff3r 347 Report post Posted March 21, 2011 Surely its not as bad as using diesel in it.... In a car which doesnt adjust the timing to stop pinging on low octane fuel, yeah it'd probably be worse than diesel. I'd imagine the diesel would simply not ignite? But I may be wrong, whereas the low octane fuel would combust unexpectedly and violently, melting your pistons and making a right mess Only use diesel if you have insects installed. I lol'd. Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted March 21, 2011 Only use diesel if you have insects installed. I don't think the E39 had the ANT option Quote Share this post Link to post Share on other sites
mossline 15 Report post Posted March 21, 2011 Does it really make that much of a difference? Ive been using 91 as it was cheaper but maybe I should spening the extra... What about Mobil's 98 octane? Quote Share this post Link to post Share on other sites
Apex 693 Report post Posted March 21, 2011 Run 95 if it recommends you do so, as said running 91 will cost more in the long run. I would not worry about your car blowing up though. I ran mine on 110 over a couple of tanks and consumption went up so it cuts both ways. Quote Share this post Link to post Share on other sites
huff3r 347 Report post Posted March 21, 2011 Run 95 if it recommends you do so, as said running 91 will cost more in the long run. I would not worry about your car blowing up though. I ran mine on 110 over a couple of tanks and consumption went up so it cuts both ways. As mentioned, a modern car has knock sensors and other engine lifesavers to prevent any major damage occurring, however they will make it a pig to drive on 91. If it recommends 95 it is for a good reason, however going to a higher octane than recommended will provide very little, if any gain as the higher octane fuels actually burn slower (and more controlled). So just run it on what its designed/tuned for and you'll be much happier! Quote Share this post Link to post Share on other sites
mossline 15 Report post Posted March 21, 2011 So what would a 1996 E39 540i be built to run on? Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted March 21, 2011 Minimum octane rating for all BMW's is 95 RON Quote Share this post Link to post Share on other sites
BM WORLD 1258 Report post Posted March 21, 2011 Minimum octane rating for all BMW's is 95 RONAMEN and so it shall be i have to tell this to people all the time theres even a sticker in most bmw's petrol cap saying so Quote Share this post Link to post Share on other sites
mtech1e30 0 Report post Posted March 21, 2011 In a car which doesnt adjust the timing to stop pinging on low octane fuel, yeah it'd probably be worse than diesel. I'd imagine the diesel would simply not ignite? But I may be wrong, whereas the low octane fuel would combust unexpectedly and violently, melting your pistons and making a right mess 2002 Nissan Sunny, FB15, 1.5L Auto. Was running a bit rough and unsure why. Engine would cut out when you came to a stop at traffic lights. Once moving it went ok. Turned out was running on two cylinders which was a bit odd. Someone had filled it with diesel. Quote Share this post Link to post Share on other sites
curryinahurry 38 Report post Posted March 21, 2011 The fuel cap of my NZ New 330, states 91-98 RON. However, I've tried half a tank of 91, pinged a bit, so i filled up the rest with 95 the next day - much better. Quote Share this post Link to post Share on other sites
sascha 17 Report post Posted March 21, 2011 My old NZ new e30 325i had a sticker inside the petrol flap saying "Use only Unleaded 91" so thats what I always used.. Maybe I should start running 98 in the m50 then? It's just so damn expensive.. I can hardly afford to run it on 91 these days.. Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted March 21, 2011 Our fuel in NZ is manufactured with additives to get an octane rating, it is not refined to the octane rating (RON) Quote Share this post Link to post Share on other sites
M5V8 337 Report post Posted March 22, 2011 what are you trying to say here Glenn? 91 is the same as 98 just minus a few additives? Quote Share this post Link to post Share on other sites
Apex 693 Report post Posted March 22, 2011 Tectron cleans my engine as i'm driving so I no longer need to change my oil. Its great. Quote Share this post Link to post Share on other sites
matt45 1 Report post Posted March 22, 2011 (edited) Only use diesel if you have insects installed.I lol'dI don't think the E39 had the ANT option I Rofl'dTectron cleans my engine as i'm driving so I no longer need to change my oil. Its great. then i Roflmao... on topic tho my sticker does say 91-98 altho ive never used lower than 95, as glen mentioned there is probably some technicality in the octane rating system. Edited March 22, 2011 by Matt45 Quote Share this post Link to post Share on other sites
Jamex316 1 Report post Posted March 22, 2011 I think 95 from shell is definitely worth it. It was really obvious in mine. It never got close to 7.8km/l on 91, and it just went straight up to 9.8km/l on 95 straightaway and even 10.5km/l at one stage. Besides that, the engine sounds smoother and obviously the response is better. I have tried 98 on my twin turbo suby before and it made no difference, cant really imagine 98 being any major improvement over 95 for the bimmer too. At least not as obvious as the difference between 91 and 95. Definitely recommend 95 for the bimmer, 91 is for lawn mowers... I was just curious to find out. Quote Share this post Link to post Share on other sites
westy 614 Report post Posted March 22, 2011 Meh. I run the 540 on 91. No probs. Dont buy into the economy argument either. Quote Share this post Link to post Share on other sites
mossline 15 Report post Posted March 22, 2011 Meh. I run the 540 on 91. No probs. Dont buy into the economy argument either. Me either, petrol is petrol. Quote Share this post Link to post Share on other sites
pjay 8 Report post Posted March 22, 2011 95 for Flybuys, Quote Share this post Link to post Share on other sites
BM WORLD 1258 Report post Posted March 22, 2011 The fuel cap of my NZ New 330, states 91-98 RON. However, I've tried half a tank of 91, pinged a bit, so i filled up the rest with 95 the next day - much better. yes i have seen head gasgets eaten away from people driving arund with pinging engines My old NZ new e30 325i had a sticker inside the petrol flap saying "Use only Unleaded 91" so thats what I always used.. Maybe I should start running 98 in the m50 then? It's just so damn expensive.. I can hardly afford to run it on 91 these days.. e30 320i 325i with a lower compression engine around 8.5:1 or 9:1 cr will be fine on 91 but say e28 535i with 10:1 cr will need 95 or higherbut a e34 535i with 9:1 cr will run ok on 91. but most later tiwncam engines are 10:1 CR so require 95 or higher Quote Share this post Link to post Share on other sites
