so i took off my upper intake yesterday to change a gasket, and i noticed that all my lower intake runners were brown inside. when i tried to clean them up with a rag, it wouldnt come off. so what caused this to happen? i'v only had this intake on for maybe 8 months. it also seemed like i had alot of oil build up on the outside of the lower intake...mostly on the right bank side, and rear of it...can anyone help me out?

 

its probably just oil burned on thats coming through your pcv system