I recently did o/c on my 2001 Buick .I went with a mix of Warren semi-synth 3qts 5w20 and 2 qts Warren semi-synth 10w30 and a STP filter.Real smooth and quiet.
QSGB is my choice , in my sig the Hyundai has 275 K and my kids cant kill it at college .
summers in "TALL Corn Country" can be hot and QSGB has stood up well for me in the Hyundai and my Buick which is a summer road car as I sell in the midwest