I do not think your 98 has an oil life moitoring system. I think that is only on newer cars. Just change your oil every 3000 miles. You have to keep track.
Service engine light is your direct link to your computer system. The light being on means the computer (AKA your fuel injection, ignition,transmision) has detected something wrong. With a scan tool you can retrieve a code that will tell you what is circuit has the issue. If the service engine light starts to blink that means further driving of the car could result in damage.
Neither of the above should be comfused with the red "oil" warning lite, AKA the dummy lite. The red light means the sensor in the motor is no longer seeing oil pressure. This would mean that major engine failure is under way and you need to shut down the motor ASAP.
Last edited by Gorn; 06-25-2013 at 08:22 AM.