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.
Dave Hinz
in article snipped-for-privacy@uni-berlin.de, Dave Hinz at snipped-for-privacy@spamcop.net wrote on 03/08/2004 03:08:
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
Hehe - how to kill a turbo in 3 easy steps...
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.
If you go to the extreme end of low octane as in some countries, then such fuel does the engine no good at all. By stretching the implication of this, one can probably deduce that higher octane is better, especially if you drive hard such that the anti-knock control mechanism becomes very active.
I find Shell Optimax very good for the engine. I think it runs smoother.
This is a very low mileage anyway. Probably not related to fuel type.
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