Just a note for those of us who drive the oil burning (ie diesel) V6, the cycle the ignition to the 'on' position and depress the accellerator 3 times in 10 seconds does not work.
I tried this a number of times after being advised by the dealership in Townsville that this was the proceedure to remove the message. Finally I decided to do some internet research and found that for the export model, 3.0lt diesel, the proceedure is as follows:-
1. Cycle the ignition to On/Run (Push the start button twice without putting your foot on the brake. Do not start the engine.)
2. Hold the accelerator pedal down for 30 seconds. (Don't let it back up)
3. Pump the brake pedal six times whilst still holding the accelerator pedal down. (Dont be concerned that the brake pedal will load up and get harder to push, just make sure that you push is down firmly and dont give yourself a hernia trying to make it go to the floor.)
4. Release the accelerator pedal after the sixth depression of the brake pedal.
5. Push the 'Start/Stop' button once. (This will cycle the ignition of 'Off")
6. Start the engine to make sure the message has been turned off.
I only had to do this once and the message was turned off. Information was from Jeep Grand Cherokee WK2 - Oil Change Indicator System
If you visit this page it has the info for both the petrol and diesel versions of the JGC WK2's Just scroll the the very bottom of the page.