My 01 Optima V6 has 93K. Change the oil every 5K miles and check the trans axle oil. Mine gotvery dirty at 60K. Changing trans oil isn't that hard. Don't let anyone charge you a lot of money. I had a trans shop quote $129. Bu two gallons of trans oil from walmart $10. One bole and 4qts out of 8 will drain. Your trans oil will be half clean because the other half is still sitting in the torque converter. At the next engine oil change, drain again. Doing this twice will get you 75% clean for $10.
I figure doing a lot of trans oils changes, more often than one by the transmission shop, at $129, is a lot better.
Believe the manual when it says to change plugs at 30K. Actually I got 90K before my car started running bad and the check engine lite came on. However, I pushed it.
Fuel filter
Plug wires - change to silicone $40, (dont go to KIA they charge way too much) at the same time you do the wires
I'm at 93 and going for 200K. Other than that, just drive
Oh, I almost forgot. I needed a battery after 42 months