My 2016 Buick Cascada had this problem before at about 68k miles. The camshaft would whine as if it's coming in contact with the upper part of the camshaft cover. I arrived at a local Buick | GMC dealership and spoke with one of the Master Technicians who stated "I've seen two same models arrive with the same problem, I recognized the whining noise coming from the engine bay, you need to replace the camshaft cover". The vehicle was under bumper-to-bumper coverage so there was no gripe until I am having the same problem. I suspect if I replace the camshaft cover there would be another incident down the road in which I would need to replace yet again another camshaft cover. General Motors should call a recall for this.