Using oil detergents in 2001 Intrepid?

My 2001 sounds like it is low on oil (chattering/clicking), however, when I check the oil the level is fine. My oil light has been flickering, mostly when I have the car stopped or in park. I thought about using some CD2 oil detergent to help with the valves and lifters, but I am kind of leary. Is there a better product to use or maybe something else entirely that needs to be done?

are you using synthetic motor oil?

No. I was using regular old Penzoil until the very last time I added oil and it was Castrol, I think.