I have a 1987 Cadillac Cimarron, It's burning oil or leaking oil. I believe it's burning oil Because of the smell, I don't think it's burning fast because it has never not been on the dipstick and I've only topped it off once. I also have Zinc additive for the oil because it's a flat tappet Cam I am not sure if that has anything to do with it. What is my best course of action for troubleshooting and what can I do if my engine is burning oil?