Get the oil from the agents. There are only two different ones from them. Diesel and petrol. Its cheap cheap. I'm not too sure on 204 but on 203 the whole sump cover needs to come off which is a pain. The oil filter housing might have the nut type of special tool type cover. Nut type then you will need a bug socket. Special tool type you can open with oil filter tool. Normal sump nut underneath. Then youtube how to reset service light. OIl filter can be purchased from gold wagon but I don't like those. I get from agents. Its not that much expensive. They don't come with sump washer so careful not to lose it. You can reuse the sump washer up to about 5 times until they eventually start leaking.