Engine Ticking PLEASE HELP!!

Just Changed the oil in my car. It's a 2006 Cobalt LS 2.2 Ecotec. I put in Royal Purple 5w-30 back in the summer because I was taking it to the race track a lot. Only other thing I've done to it is added a cold air intake for more power. Everything was just fine with the car until I changed the oil back to Regular Pennzoil 10w-30 3 days ago for the winter but as soon as I changed it the car starting ticking and when it idles it sounds like a mini diesel!?! :crying: So I Put STP oil treatment in it..still ticks. Changed from reg. pennzoil to Synthetic Pennzoil..Still ticks. Well the guy at Advance auto said it was from going from the best synthetic to a cheap non synthetic oil..well..I put Royal Purple in it and put a Lucas gas treatment in it....STILL FREAKING TICKS and my engine light is on!

Any Ideas?! I could sure use the help...