See also:

Explanation of scheduled maintenance items
Engine oil and filter The engine oil and filter should be changed at the intervals specified in the maintenance schedule. If the vehicle is being driven in severe conditions, more frequent oil an ...

Roomy New Interior
However, the Optima's quiet new interior is more upscale and will accommodate four tall adults, or five in a pinch. Front seats are supportive, and the rear-seat area is impressively roomy—alt ...

Rear differential (4WD)
Checking or changing rear differential fluid Have rear differential fluid checked or changed by an Authorized Kia Dealer according to the Maintenance Schedule at the beginning of this section. ...