kawilt,
First I gotta say $2000 sounds like a lot of money for 2 elbows. Does that include fabrication and installation? I bought mine off the shelf just like the elbows I replaced. I looked through my receipts, but couldn't find what I paid. I'm thinking they were $800 for the pair, but I could be wrong. But if it takes $1000 per engine to return to service, I bet it'll be money well spent.
Oil analysis without a baseline is almost meaningless....especially with only 10 hrs on the oil. If you're going to rely on it as valid data, you'll need to sample before replacing the oil, then continue in similarly in the future to establish a baseline to be able to watch for a trend. I haven't done any analysis on my oil. I just change it every 200 hrs. At 2000 RPM, I find I need to add a quart to each engine every 50 hrs or so. (I just looked in my log today on the way home and it had been 50 hrs between oil 'top-offs'.)
My 4.236's are 1977 models so they're pushing 37 years old. I bought the boat in 2007 with about 2300 hrs. They turned 2900 hrs this week and are running great. If it took 37 years to build 2900 hrs, they've got MANY years of good service remaining assuming proper care and feeding.
I run them at 2000 RPM for 7.5 kts at a consistent 3.0 GPH. The PO did the same. My plan is to keep them fueled, oiled, and cooled. That requires stuff like fuel system maintenance, zincs, coolant changes, oil/tranny and water heat exchanger servicing and impeller service (@ 200 hrs).
I hope you get similar results.