*0W20 or 5W20 scares me in the Theta II 2.4L GDI , I bumped up to 5W30 synthetic oil for the higher HTHS as well as to guard against fuel dilution of the GDI engine.I doubt oil grade is going to change anything to prevent the rod bearing problems. If the passage is clogged, bearing will fail eventually. The noise test done by the dealer should have detected it already anyway.
I check the PCV and do a GDI cleaning every year. I use 0w20 full synthetic every 6000 km (anything on sale: mainly Pennzoil, Castrol or Shell) in my 2015 Optima and it's working perfectly: no strange noise, no oil consumption. This car does a lot of stop and go and short trips during Canadian winter. No complaint so far.