Unless Kia changed their recommendation, you can also use a 5w40 in that engine. That's what I used when I had a '12 Optima turbo. I would certainly use a synthetic, whether 5w30 or 5w40.
wemay said:Unless the manufacturer requires syn, im not buying it anymore (I once was a 'syn for every turbo' guy). As long as you stick to to the owners manual OCI and oil specs, you will be fine. The Santa Fe Sport 2.0T GDI requires 5w30 SM GF-4 (section 8.7). It also states that if not available, SL (section 8.8) and 10w30 (section 8.9) is acceptable. 5k -normal / 3k - severe oci. I'm sure the Optima's requirement is different but it still does not require syn. I will trust the guys and gals who designed, tested and built these engines.
The same ones that don't care once car is out of warranty so you hopefully buy a new car?!?
ummmmm....yeah, might be going back to syn blnd or syn. Timing chain stretch concerns me too.