91 - Check Oil light

[namatarr]

I have a 91 Buick Park Avenue. I bought the car last year and it has been parked in a garage for a little under a year. I had a mechanic check it over and replace all the fluids, oil, and filters. I noticed that my Change Oil Soon light is on. I followed the directions in the book with reseting the system by holding in the switch for five seconds. I do this and the light blinks four times and goes out. However a few seconds later the light comes back on. I've reset it about 10 times with still no luck. Does anyone have any ideas what it could be??

Thanks in advance.

[DioGreer]

What oil pressures are you getting on your oil gauge at idle and around 3000 rpm?

[namatarr]

At idle the guage reads about 60 and at 3000rpms the guage reads about 80.