I have had my 2005 SRX into the dealership 4 times trying to solve a loud sticky lifter or a water pump bearing going bad sound. The dealership and GM claims it is carbon build up from using high octane gas. The dealership did several de-carbonization cleanings of the engine without any luck. They even poured a quart of Zmax Micro Lubricant into the engine to stop the sound. Has anyone else experienced this problem?