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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. ...

Impressive Warranty
Hyundai is Kia's corporate parent, so the Optima gets Hyundai's impressive warranty; it includes 10-year/100,000-mile powertrain protection and 5-year/60,000-mile roadside assistance. Kia is put ...

Automatic transaxle
Checking the automatic transaxle fluid level The automatic transaxle fluid level should be checked regularly. Keep the vehicle on the level ground with the parking brake applied and check the ...