Date: Tue, 03 Aug 2004 22:47:31 -0700 From: Brent Riggs <riggsappealtakethisoutnospams.com> Subject: Re: Octane rating effect on engine wear?
Paul Halliday wrote: > in article 2n8ac0Ftmn15U1nospamberlin.de, Dave Hinz at DaveHinznospamcop.net > wrote on 03/08/2004 03:08: > > >>On Mon, 02 Aug 2004 18:09:29 -0700, Brent Riggs >><riggsappealtakethisoutnospams.com> wrote: >> >>>The user's manual says the 9-5 will run just fine with lower octane >>>fuel, but also says it was designed to run on higher octane. My 2001 V6 >>>seems to run well on the lower octane. But I was wondering about engine >>>wear--does the octane level affect it? The dealer just had to replace >>>the turbo unit under warranty with 40,000 miles. >> >>Nope, I can't see any way that lower octane fuel would have any effect >>on turbocharger wear, either more or less. Lower octane fuel will >>allow the engine management system to make less boost for the >>engine, that's about the only thing ocane effects. > > > The V6 is turbocharged? You learn something new every day! > > Going back to the old days, SAAB's APC allowed their turbocharged engines to > use octane fuel low as 91 RON. SAAB's more modern engine management systems > will do exactly the same. The benefit of using a higher octane fuel (say 97 > or 98 RON) with turbocharged engines is that higher boost is more reliable > and less prone to "knocking". Given that SAAB have used knock sensing > systems since 1982, there's no risk to your engine or turbocharger. > > Certainly for the older turbocharged cars, it is wise to allow the car to > settle for as generous amount of time as you can when the car comes to rest. > The turbo can still be spinning at very high RPMs when you shut the engine > off. Many people with older turbos make up some kind of routine when coming > to rest, like putting up the windows, removing stereo head units, adjusting > hair/tie/whatever for between 30 and 60 seconds before switching the engine > off. > > What does your handbook recommend you do? > > I looked at an old 900 turbo once that the owner had to replace the turbo > within 6 months of owning and was selling it with around 4 months on the > turbo. It sounded like a helicopter taking off. I quickly realised that he > lived on a slope and booted the car off the line before it was warmed up and > drove it hard, switching it off before it had come to rest. I was not > surprised the charger was showing signs of failure. > > Have a think about how you drive it. > > Paul > > 1989 900 Turbo S > http://saab.go.dyndns.org/ > Oh, I used to be a hotrodder, but that was when I was a young single guy with a brand new 440 cubic inch 4 barrel Dodge Charger R/T. Now I'm an old guy who likes to drive slow and hold up traffic on the freeway. Maybe I don't drive it fast enough, but I don't see the manual recommending anything I don't do, which is why I thought maybe the fuel octane had killed it. Anyway, it sounds like I don't need to switch fuels. Thanks for the input. Maybe I'll buy a stereo head unit so I can take that off while the turbo settles down.
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