LM,
The Series 2000, 0w30 can be used to replace 5w-20/5w30/10w-30 oils. I'd even recommend it in engines that come with 0w-40 or 5w-40 grades. Wear protection is at least as good as the Amsoil 10w30, but with a few percent better fuel efficiency. I've run just about everything Amsoil makes in my Audi 100, and the 0w30 generated the lowest oil temps and the highest fuel efficiency. Compared to the Amsoil 10w30 I used to run, I consistently picked up about 3% in fuel efficiency.
There really is little call for a 10w-40 for most modern gas engine applications. Most of the Amsoil 10w-40 I sell is for diesel engine passenger cars and Japanese motorcycles.
If your SAAB is in good mechanical shape, the 0w30 will work just fine ....
TooSlick