Oil commonly leaks from the valve cover gasket requiring replacement of the gasket. Oil will be visible at the top of the engine and possibly in the center area around the spark plugs.
Resources for the Repair and Maintenance of your 1998 Saab 9000
1998 Saab 9000
1998 Saab 9000 Problems
The head gasket can fail causing the coolant and oil to mix in the engine, and external leaks. Symptoms can include overheating, white smoke from the tailpipe at start-up or acceleration, and the visible presence of oil in the coolant expansion tank.
The water pump can fail causing noise on the left side of the engine and overheating. Other symptoms include coolant loss and leakage at the front/left area of the engine.
Oil can leak from the oil pump cover seal. Oil will be visible at the bottom and left side of the engine, behind the crankshaft pulley. The seal will need to be replaced.
The direct ignition cassette can fail causing the engine to die while driving, and/or it will crank but start. Diagnosis may also discover trouble codes for random misfires.