As owner of a 1999 Nissan Maxima, 2005 Nissan Pathfinder V-6, and a 2008 Nissan Titan V-8, my son and I would be interested in learning just what OHC problems Nissan has had that might require synthetic oil to be restricted to a dino-like 5,000 mile OCI. My Pathfinder presently has 7600 miles on M1 10W30 HM, and has used about a third of a quart in this time. Oil looks very good. I'm doing a one year OCI, which should be almost exactly 10,000 miles.