Hi I had an oil change done the other day with Triple QX Sythetic 5W/30 and a Bosch oil filter. Last night starting up the car in the frost to go home from work I heard a really bad knocking almost like banging from under the bonnet which slowly subsided after about a minute or two. It did it this morning as well, and its been below freezing when starting up each time, its not like valves ticking it sounds like metal on metal hitting like someone has a hammer tapping the bonnet. The car runs fine after that its just pretty worrying. I have a 05 2.0l WRX blob eye about 120k on the clock. The garage told me they put 4.3l in and it showed nothing on the stick, so they filled it up using 4.7l of oil in total.