Change Oil Soon Display

Hi all,

I have recently become the proud owner of a two year old Astra SE. It was supposed to have been serviced by the Dealer when I bought it but after doing 4,000 miles I have the 'change oil soon' warning.

I assume the Dealer didn't bother to change the oil so I will get it done.

Anyway, I just wondered what triggers the warning. Is it mileage that is preset or is there some kind of censor that can monitor the condition of the oil. Also because I work away I'll do another 500 miles...

Change Oil Soon Display