The oil pressure is dropping to below the set point of the sender while at low RPM's. The AC incresses the RPM rate and so does just driving.
On the gas gauge where the speedometer and RPM's are
have vehicle scanned to determine the problem
The 2004 Kia Optima has 16 valves.
The 2004 Kia Optima has a 5-speed manual.
The 2004 Kia Optima has an inline 4 engine.
The 2004 Kia Optima is a gas-powered vehicle.
the answer is on this same page before yours
The 2004 Kia Optima is 15 ft. 5.8 in. (185.8 in.) long.
The 2004 Kia Optima's turning circle is 34.1 ft..
The curb weight of the 2004 Kia Optima is 3281 lbs..
The 2004 Kia Optima has double overhead cam (DOHC).
The 2004 Kia Optima runs on regular unleaded.