Question 1: Oil change at 9.3

Greetings, dear Swedes, a question: my Saab (9.3 Aero Cabrio with Hirsch Step 1, lots of city traffic and short distances) has about 22,000 km down after one and a half years. Last autumn the inspection light lit up for a time – km stand about 17,000. Now someone has told me that this happened because the car needs an oil change. Is that true? PS.: The lamp has not been shining for a long time – if someone wants to ask about it. G Ruß OLLI