We have a 2017 Hyundai Santa Fe SE with the 3.3L V6 Lambda engine. We bought the car brand new in May 2016, and it has about 31,000 miles on the odometer. I've always done the oil changes at the dealership and brought my oil. Since new, I used Mobil 1 5w-30 EP in the engine and did the first oil change at 4100 miles. Last year the dealership changed its policy, no longer allowing customers to bring their own oil. I was hesitant but needed to change my oil, so I used their oil. They claimed it was Pennzoil Platinum 5w30. I was a busy time in our life, so we did about 7500 miles on that oil change. I looked at the oil cap and oil filler hole and noticed some brown varnish, possibly oxidation. Sure enough, I decided against going back to the dealership ever again for an oil change. After reading so many good things about Pennzoil on this forum, I doubt that I really got Pennzoil from our Hyundai dealership. I ordered Pennzoil Ultra Platinum 5w-30 on Amazon and did the next oil change at home (bought a nice torque wrench as well - Craftsman). My wife put about 2000 miles on the Pennzoil Ultra Platinum, and I decided to change the oil again, to completely clean out the crud that the dealership put in. Because I saw what a great job Castrol Edge did cleaning the engine in my 2018 Hyundai Santa Fe Sport, the 2.4L, I decided to switch her car to Castrol Edge Extended Performance 5w-30. I also installed a Votex DP001 magnetic drain plug in her Santa Fe SE. Anyway, the startup noise that you're about to hear in the YouTube video bellow started happening even before I began doing our own oil changes. I am wondering if anyone else here that owns a KIA or Hyundai with the 3.3L V6 Lambda engine has or is currently experiencing this. It sounds like a timing chain rattle due to a bad tensioner. It only happens after the vehicle has been off for many many hours. From my research, it seems that this happens when the teeth on the tensioner are ground, and once the tensioner is drained of oil, the teeth can't keep tension on the timing chain any longer. Notice that the rattle happens right after ignition, once the engine starts turning on its own. Your input is more than welcome. I am sorry if my post is a bit longer, but I tried to offer the entire maintenance history of this vehicle as far as oil changes are concerned. However, I don't believe that the issue at hand is due to oil changes, especially since most of the time we went with 5000-mile to 6000-mile drain intervals.