You can set the oil change service interval in the EVIC. As soon as you have reached this interval, you will get the "perform service" message. After changing the oil, you will have to reset the service interval on the EVIC.
JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.