My tuppeneth for what it’s worth.
Got a mate that runs a Saab specialist and a father in law with a 9-5 on an x reg
the specialist says all individual models have different problems but each model will have certain problems.
As for the 9-5 it has problems with the filter in the sump sludging up which can kill the engine. Changing this filter means removing/possibly destroying the lovely original double skin exhaust plus labour so father in law has chosen regular fully synthetic oil changes instead.
His car had a problem losing water when he bought it which turned out to be a batch of models that the factory hadn’t tightened the headbolts properly. Local garage tightened these and no problem since.
Good luck
sorry if I’ve rehashed previous threads and my moneys on a 2l mondeo with the timing chain!