The engines crank case needs to breath through a crank case vantilation system, and that used to mean directly to atmosphere. Today's diesel trucks are now vented directly to the air intake system which is not good for your engine. The air is entrained with oil and causes buildup in the intake system, intercooler pipes and intercooler. This can lead to poor performance and can affect the life of the engine. Alligator Performance works with the top brands in the diesel performance industry that make PCV re-route kits, such as Deviant Race Parts, BD Diesel, Fleece Performance, Maryland Performance and Pusher. If you have any questions, contact firstname.lastname@example.org and we would be happy to assist you.