Noisy lifters can be caused by oil contaminants in and around the lifters. It can also be cause by a blockage in the tiny vent hole in the lifter itself. I would recommend running a basic application, which is merely adding a full bottle of Auto-Rx in with your next oil change and filter. I suggest running a conventional oil for the cleaning run of 3000 miles, followed by a rinse phase of 3000 miles on conventional oil. I assume this Buick has the 3800 series motor, which is not a motor prone to any serious sludging issues. Does the loud ticking occur only if the car sits overnight? Or will it be loud if the motor is shut down for about an hour and refired? I ask this because some folks have had good luck running the maintenance dose, after the initial cleaning and rinse. The polar of metal attraction properties of Auto-Rx help keep a better film of oil on the metal surfaces after shutting down. Kind of like some protection against dry starts.
