Kia Optima OE Engine Coolant - autozone Order Kia Optima OE Engine Coolant online today. Free Same Day Store Pickup. Check out free battery charging and engine diagnostic testing while you are in store. Kia Optima: Checking the coolant level - Engine coolant If frequent coolant addition is required, see an authorized Kia dealer for a cooling system inspection. Recommended engine coolant. Use only soft (distilled) water in the coolant mixture. The engine in your vehicle has aluminum engine parts and must be protected by an ethylene-glycol-based coolant to prevent corrosion and freezing.