Young Thrash Driver 1020 Report post Posted May 1, 2007 I know this question will make me sound like a cabbage but I wanna know, so here goes... Is my E36 325 OK to run, long term, on 95 and 98 fuel? The BMW booklet in the glovebox says "Dont do it!" but I'm not so sure if thats just them covering their butts in case something goes boom Quote Share this post Link to post Share on other sites
kerrynzl 3 Report post Posted May 1, 2007 The M50 engine has 11:1 compression ratio so it needs te highest octane it can get. the M50 also has a knock-sensor which retards the ignition to prevent detonation when too low octane is used. When the engine has retarded ignition the engine loses torque, so you need too use more throttle to compensate [less economy] Low octane with a knock-sensor wont do any mechanical damage,but you'll be using the engine outside what it was designed for for an extensive period of time Quote Share this post Link to post Share on other sites
bravo 34 Report post Posted May 1, 2007 What kerry is saying is run the higher octane. Engines that have been run on a particular octane rating for a long time sometimes don't run so well when changed, but this is complicated as there are two different types of octane ratings and the one that matters isn't the one labeled at the fuel pump. I won't get into all that here esp. as I am no expert, but long story short, run it on the higher octane, if you don't notice particularly poor fuel consumption or "pinking" then sweet. Quote Share this post Link to post Share on other sites
kerrynzl 3 Report post Posted May 2, 2007 Hey! Our 95 & especially 98 is good fuel, the only thing missing from it is tetra-ethyl lead used to stop valve seat reccession on old soft cast iron cylinder heads. the old 96 super they had years ago was good for 9-1/2 to 10:1 compression max [petrochemistry is a real science these days] Quote Share this post Link to post Share on other sites
Young Thrash Driver 1020 Report post Posted May 2, 2007 Cheers guys. lol nice to have people who know what they're on about... Quote Share this post Link to post Share on other sites
duggybuggy 0 Report post Posted May 22, 2007 I know this question will make me sound like a cabbage but I wanna know, so here goes... Is my E36 325 OK to run, long term, on 95 and 98 fuel? The BMW booklet in the glovebox says "Dont do it!" but I'm not so sure if thats just them covering their butts in case something goes boom that u colin? Quote Share this post Link to post Share on other sites
m325i 705 Report post Posted May 22, 2007 tetra-ethyl lead Worst thing EVAR! Quote Share this post Link to post Share on other sites
