I do not have the owner's manual for my Optima and do not know what is the best oil weight for my car?
Motor Oil on 2004 Kia Optima
i do have the manual mail me firstname.lastname@example.org
take it to your local dealer they have everything you need to know.....5w20....???????
Kia call for SG or SH spec oil. They call for 10/30W for ambient temps between 0 to 90 degrees and 10/40 for temps between 0 and 120 degrees. If your car has high mileage I would use 10/40. With oil filter change you need 5 quarts total.