I have a 2012 lt2 with the 1.4t and during the colder months I've been getting an odd squeaking noise, almost like a belt tensioner chirp though it was not the belt or tensioner, under the valve cover. It has about 92k on it and I've stayed current on all oil changes. No mods, turbo went out a couple of years ago at around 80k. Dealer did service on it. Any ideas on the cause?