Timing Belt or Chain ? on 2005 Saab 9-5

I have a 2005 9-5 linear wagon. Do I have a timing belt or chain and
when should I replace it ?

Asked by for the 2005 Saab 9-5
It looks like all the 9-5 SAABs have timing chains, which take about 11 hours to do, the engine has to come out of the car to gain access. If you change your oil every 3000 the chain can last for the life of the car, if you wait on the oil changes then the chains can go in less than 100k.
I know the factory manual says wait until 5000 or even 10,000 miles before and oil change, but ask your self this question, did the chemistry of oil really change that much in the last say 10 years? I think not. I use Mobil 1 fully synthetic and replace the oil and filter every 3500-4000 miles and I only have a 4 cylinder Camry, which is a pretty pedestrian car.