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/