Here are great, straightforward instructions on how to reset your late C4 oil light. The instructions come from Top 50 questions From Corvette Owner’s and Dealer’s with Answers by Gordon Killebrew.
The change oil light will come on after the CCM has seen certain operating temperatures, engine RPM’s, and load conditions. After the oil has been changed, the CCM should be reset so that the light will turn off, and so that CCM will know the oil was changed.
Reset Procedure:Turn the Key in the “ON” position, leaving the engine off.
Press the “ENG MET” button on the trip monitor and release. Again, press the “ENG MET” button and release.
Next, Press and hold either the “Range” button (1990-1991), or the “Gauges” button (1992-1996) on the trip monitor. The Change Oil light will start to flash, keep holding this button until the light goes off completely (usually about 10 seconds).
If unsuccessful, turn the key into the “Off” position and start this procedure again.
When successful, the engine oil life monitor will be reset and the light will be off.