I'm looking at used Saabs, and I know generally the models that are sludge prone, but there seems to be some ambiguity concerning the 1999 9-3 and Aeros. Some say '99 is a sludge year for 9-3s, and other say that sludge starts in 2000. I also see some differing opinions on 9-5 Aeros. Some say they are less prone. Any way to clear this up?