I agree that the "wrong" octane should not fail you. Theoretically the higher octane either won't improve the combustion or might even make the car run worse. In reality (as far as I can tell) the only difference, besides the obvious price differential, when I use a higher octane than the car manufacturer recomends the motor seems to run cooler and I get slightly better mileage. These effects are not enough to justify the higher price. Using lower octane than recommended can have serious effects over a long time. I suspect not as much as in the past because most cars have knock sensors so if the octane is too low the performance will just be degraded. More important than octane is leaded vs unleaded. Using leaded gas (if you can still find it) is a BIG no-no. It will quickly contaminate the catalytic convertor. David Teitelbaum vin 10757 --- In dmcnews@xxxxxxxxxxxxxxx, "Harold McElraft" <hmcelraft@xxxx> wrote: > > There are differences - that's true but, it is a remote possibility > that fuel octane is the reason the engine is failing emissions tests. > I've run premium for years and mine tested in July 2005 as clean as > To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/