Chuckbizkits; WTF?! It's been a couple of hours and you expect this cat to do a full blown analysis? My guess is he's got a job and he's working. Why be so hurtful and not helpful? Now you're going to pay him the full cost of his car if it's not the builder's fault? Why not just drag race him to settle this? Oh, you already went down that path.
Here's my guess: Too much crankcase pressure blew out the silicone seal on the the valley tray that the builder installed. Not going to pay for his entire car if I'm wrong but worth checking out.