Just put a brand new rebuilt 351W long block in my boat. I fired it up for the first time, ran it less than 2 minutes, and the oil is already turned to choc. milk. That's a bunch of water in a short period of time. How likely is it a bad intake manifold? I did use the old intake manifold off the old engine. I thought it looked fine so I just cleaned it up and bolted it on the new engine. I put all new marine gaskets and followed proper torque procedure. Guess I should have had it checked. How much should it cost to have it magnafluxed? Who does that sort of thing?