Jwiggs152

So anytime my truck sits for more than a few hours I get this noise on start up. Generally last about 20 seconds and then it goes away. No issues in performance or anything other than this sound. I thought it might be drain back because carmax put a garbage filter on it with no check valve. Ive had the truck just over 3 months put less than 3k miles on it currently sitting around 47250 miles. I changed out the oil and filter and it still makes the noise. Does anyone have any ideas. It is the 5.3 l v8 . Here is a video of the noise.