Kia Optima: Checking the Coolant Level
WARNING - Removing Radiator Cap

Check the condition and connections of all cooling system hoses and heater hoses. Replace any swollen or deteriorated hoses.
The coolant level should be full in the radiator and between F (Full) and L (Low) on the coolant reservoir tank when the engine is cool.
Check the coolant level using the dipstick attached to the reservoir cap.

If the coolant level is low, add enough coolant to bring the level to F, but do not overfill. If frequent additions are required, see an authorized Kia dealer or another competent repair center for a cooling system inspection.
Engine Cooling System
Changing CoolantCruise Control
The cruise control system allows you to program the vehicle to maintain a constant
speed without resting your foot on the accelerator pedal.
With cruise control, you can set and automatically maint ...
Inspection
Front brake disc thickness check
1.
Check the brake pads for wear
and fade.
2.
Check the brake disc for damage
and cracks.
3.
Remove all rust and conta ...
Overdrive Clutch Control Solenoid Valve(OD/C_VFS). Description and Operation
Description
Overdrive clutch control solenoid valve(OD/C_VFS) is attached to the valve body.
This variable force solenoid valve directly controls the hydraulic pressure inside
the overdrive clutc ...