Just finished up the install on my "New to Me" Yanmar 4LH-DTE engine. After a couple of trials on the local lake, I realized my oil pressure seemed high. I put in a mechanical gauge, and verified that it was idling hot at about 60 psi, and goes up to 80 when I surpass 1800 RPMs. I had changed the oil and filter while it was on the bench in my garage. I had put 15W40 in it and a factory oil filter. After seeing the high oil pressure, I put half a can of Seafoam in the oil, and ran it for about an hour a day 5 days in a row, then changed the oil to 10W30 and put a new oil filter in. The oil pressure is now about reading about 50 PSI hot idling, and now hits 80 at about 1900 rpms, so I saw a difference, but not enough to make me comfortable. Does anyone have any ideas what might be going on here? Does that oil pressure seem excessive to you? Thanks in advance.