http://www.autoherald.co.kr/
There's a write up in Korean my iPad won't translate . Here's another showing 30 is legit.
http://www.hyundaisonatamanual.com/sonata296recommended_lubricants_and_capacities.html
I got it from the Hyundai forums where they say it's just another part of the long sad saga of the Theta 2 engine series,
The skinny from the Hyundai forum as a general consensus is this. keep it always synthetic oil, period. Then change that oil AT LEAST every 5000 miles . Then maybe...¬ it will be fine. As for filters that's a tough choice . Their OEM is a 25 micron filter, sort of mid range. A better one would be in order but here's the kicker. Hyundai way back in the dark ages of this mess with Theta2 put out a service bulletin mandating OEM filters. They were denying warranty claims for some based on just that. Then along came the law suit and recall spanking and they behaved themselves with a 100k / 10 year warranty extension on powertrain.
Now the Theta2 being direct injection is one dirty running mother and many say that 25 micron filter is too porous to catch much of the sooty spooge that the thing spits right back into the oil, flakes off the valve stems and gets ground up ect. So which do you use, good question. You're sorta screwed either way really.
Also recently Kia has been suffering from these same engines🤫. At least their extended is supposed to be 200,000 20 yr which is a heck of a lot more reasonable if you're a car keeper. I'll bet my pension that Kia will have the same rampant issues as time gots on.
When you look at the whole long term mess it becomes clear. They don't know what or simply cant fix this problem with sudden oil consumption , bearing spinning and debris plugging up the oil journals. If they had it would have happened long ago . After all it started in 2011, crawled into view in 13 when they said it had been remedied on 4/12 with that new block cleaning process in Alabama. The dead engines just kept coming ever after and even now continue to happen. So far they've budgeted $885 million to fix warranty dead engines. Today the secret weapon is a knock detector computer flash 🙌ðŸ½That keeps them paying for the tow as you drive your car in limp mode to the nearest dealer to get its new engine before it dies on traffic. That campaign just started so will surely expand in time. And as they say " The hits just keep on coming". They're catching on fire👌ðŸ¼
https://www.autoblog.com/2018/10/18/hyundai-kia-senators-engine-firws/?guccounter=1
The good news on this one though according to whispers is that it's the mechanics fault. Supposedly they're damaging something on the fuel system while installing that 🙄warranty new engine. Time will tell.....
Last but only the icing on the cake ( only for those of us blessed with one) hop on one of the online trade in calculators and punch in your ride💸💸💸💸💸. That trade in value drop faster than Stormy Danials G string. One guy on the forums said he took his Sonata in to one place for a trade and the dealer wouldnt even take it. 🤗