Oil light
 

Hi there. I have a 2000 Grand Marquis. I bought it a month ago with 120 000 km on it. Decided to change ther oil. Went to a garage near my place, and a mechanic put in Brad Penn 5W30 synthetic oil in. Idont know the kind of oil there was in a car before. Next morning my oil light on the dasboard came on when I first started the car, stayed there for a minute or two, after the car wormed up a bit, light went off. Now pretty much everytime the engine is cooled off, same thing happens. Light comes on for a minute or two. Would anybody have had that happen or have an idea what that is?