Hey there! I've got some experience under my belt after dealing with a similar kind of bugbear on my 2016 Kia Optima, so I might be able to shed some light. Not a car expert, but I know a thing or two from dealing with my own vehicles. In my case, the culprit was the valve servomotor - it had gone defective. Took it to my local workshop where they diagnosed the issue and replaced it. The repair set me back about 405 Euro, but it managed to nip the problem in the bud. For your situation, understanding the complete scenario is vital. Could you also specify the total mileage, the VIN and recent changes (if any) you made to the Optima? Having additional info will help in giving you a more accurate diagnosis. Hope you get it fixed soon!

Appreciate the feedback! The mileage is exactly at 145337 KM. I haven't made any recent modifications, and the latest service was about 4 months ago. The VIN is confidential for me, hope you understand. I must say, I didn't consider the valve servomotor, but it matches with what I am experiencing. I suppose I should drop my car at the workshop and have them check out that specifically. The cost seems manageable too. Many thanks for sharing your experience! Let's see how it goes. Cheers!

No problem, happy to help! Yeah, the mileage is pretty high. Older vehicles can start showing these kinds of wacky symptoms. No need to share your VIN, just thought it can sometimes help with issues specific to certain build dates and such. Don’t worry about it! Absolutely, get your workshop to check the valve servomotor and the overall camshaft adjustment. Given your symptom description and my own experience, it seems like a good place to start. You never know, the actual issue might be just around there. Oh, and while you're at it, get them to check out the oil pump and the engine block too if possible. Those metal shavings in your oil are a worry, I won't lie. That might hint at a more serious problem, maybe some internal wear or damage, it's better to be sure. Good luck with the process. Fingers crossed it's just the servomotor acting up. Looking forward to hearing how it goes, keep us in the loop! Safe driving!

Alright, that's sound advice. I'll definitely include your suggestions about the oil pump and engine block in the workshop visit. Definitely don't want any unnoticed extensive damage making things worse. I've got more direction now, and I'll make sure to keep you guys posted once I've got some answers. Hopefully, it won't be too complicated. Thank you again for the guidance, appreciate it a bunch. Fingers crossed! Drive safe, everyone!