2005 1500 5.3 Vortec 4 Wheel Dr. Silverado Z71 Subject: Major OIL leak in intake manifold/head gasket on 2005 5.3 Z71 Oil is spraying under the intake manifold on the valley plate between the heads Hello, I posted a few times here, but nothing like this. My engine has been leaking oil for a while. Now I opened up the hood to see oil all over the top of engine. Could this be a cracked head? What are the symptoms? Oil in the valley leading to the intake manifold, which is also covered with oil. I would appreciate any replies or suggestions. Thank you.