I was just thinking that if he's not showing any water in the oil and he's not leaking any oil, it could possibly be a leaking diff. that is causing the film on the water. Just a thought. Also to the OP, when's the last time you cleaned the motor? Could be residual, do a thourogh cleaning of the motor and then watch for leaks, it dosen't take much oil to cause a large film spot in water.
Snorkled with extened vent lines
27" mudlites, ITP SS212's
710 BBK and hot cams mudbuster
HMF Utility series slip on pipe
2013 Rancher 420 AT.