How to Reset the Engine Oil Life System

WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.

With the brake pedal released, depress and hold the engine start/stop button until ignition on/run engine off mode is entered.
Using the right steering wheel control SEL button, navigate the menu until the oil life monitor appears. With the monitor active, press and hold the SEL button until the monitor resets.
Press and hold the reset button until the DIC display shows ACKNOWLEDGED.
Depress the start/stop button once to turn the ignition off.

The system is reset when the CHANGE OIL SOON message is off.

If the CHANGE OIL SOON message comes back on when you start the vehicle, the Engine Oil Life System has not reset. Repeat the procedure.

Alternate Method

With the brake pedal released, depress and hold the engine start/stop button until ignition on/run engine off mode is entered.
Depress and release the accelerator pedal three times.
The life monitor display should now read 100%.
Depress the start/stop button once to turn the ignition off.