Spent some time looking at the filter, and found a number of pieces of rubber, which are certainly from  installing the hose fittings.  Also found a couple  curly bits of aluminum drill shavings from the evap core.  Finally,  I found what appears to be tiny metallic flakes in the oil that was sitting in the bottom of the filter  housing (Peterson, inline filter assembly).  You can’t feel them, and can only see them in a thin layer of oil with a light shining on it.  I believe this could easily be aluminum  dust that was trapped in the evap core from when I cut the holes to install the fittings.  I last cleaned the filter housing when I installed the recently failed evap core, so anything that was in that core, would have been trapped by the filter.   

Next step will be to scrape the bottom of the pan , as suggested, with a wire through the oil drain.  I’ll also raise the tail and try to drain a bit more oil from the pan.  If there’s any sign of metal flakes in the pan, it’s game over, and the engine comes apart.  If it’s still OK, I’ll fire it up briefly without the oil cooler (since I don’t have one), and see if it blows oil smoke.  If that’s OK, I’ll figure it’s go for a new oil cooler, ground testing, and eventually, flight testing.     

Cheers,

Rusty (jury still out)