Kia has their own transmission fluid that is recommended for their cars. You can get transmission fluid for the Optima at any Kia dealer.
Sp ii sp iii
The 2005 KIA Optima can use any automatic transmission fluid (ATF) with specification meeting at least SPII or SPIII. Valvoline's Multi-Vehicle-ATF and MaxLife DEX/MERC meets the KIA specification. The actual KIA factory fluid is part# UM010-CH002, in 1-quart bottles. Always check the rear of the bottle and or the ATF's product data sheet to verify current specifications.
Dexron III.
The recommended automatic transmission fluid for the 2005-2007 Mustang is Mercon V automatic transmission fluid
Toyota ATF Type IV is the only recommended fluid.
The 2005 Kia Optima has double overhead cam (DOHC).
Dexron III
Dexron lll
ATF+4 automatic transmission fluidATF+4 automatic transmission fluid
Manual transmission fluid type ....... MERCON automatic transmission fluid. - Haynes Manual #36071 - 1993-2005 Ford Ranger Pick-ups.
1993-1996 automatic transmission: MERCON automatic transmission fluid (NOT MERCON V) 1993-2005 manual transmission: MERCON automatic transmission fluid (NOT MERCON V)