If the light is yellow and has a picture of an oil can it is the oil level indicator. As I get near the end of my 3K oil change interval, my oil level has dropped by about one quart, when it gets down one quart the oil level lamp will come on when the engine is running over 3K rpm for more than a couple minutes. What I surmise is happening is the oil is being pumped faster than it is returning to pan which causes the level to drop enough at speed to trigger the lamp.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.