Hi i have just bought an astra coupe 2.2 yesterday..iv noticed on the trip computer screen it says check oil level..which i have done..and it is at correct level. also the engine oil light came on in the dash..aswel as the cooling fan kicking in as soon as i started up the car from cold start..once i switched ignition back off and on again the light in dash and the fan stopped and the car ran as normal any ideas wht is causing this and wht solution is please?