[1st Method]

WARNING: This page is about a different car, the 2017 Kia Forte5 and 2017 Kia Forte Koup. However, it is still accessible from the selected car via links, so may be relevant.

Start the engine and keep the engine running at idle for 2 minutes.
Step on the accelerator pedal and hold it steady at 4500 rpm with the shift lever in N position to warm up the engine until the temperature of the engine coolant reaches 80°C.
Keep the engine running at 2500-3000 rpm in the N position for 15 minutes.

Fig 1: Engine Running Timing Pattern

Courtesy of KIA MOTORS AMERICA, INC.