Guys I need your help. The other day I was leaving work and noticed allot of blue smoke coming from 01 CTD out the exhaust. It never has used on before and I don't race or pull loads with it. Mostly highway driving. I do my own oil changes with shell 15w-40 . I pulled over checked the oil it was down 1. 5-2. qts. Could this be a valve, manifold gasket or turbo??? There is residual oil on the out side of the tail pipe that was never there before. Thanks guys Brian