Thanks Dave (& Mike), I had a good talk with Amsoil Jim and he assurred me that the "backwards filtering" of the past 25,000 miles is unlikely to have caused any engine damage,.. Filters still supposedly functioning, just backwards. I was having trouble getting the Donaldson 553411 filter, so I am currently using a Wix 51411 instead (recommended by Amsoil Jim as equivalent), along with a new Amsoil EaBP-100 bypass filter, both changed when I swapped the hoses. I'm waiting for the results of the Blackstone oil test, but Amsoil Jim thinks that my Amsoil DME oil change with 4000 miles on it is probably still fine.
As far as the CEL issue and sporatic flashing overdrive "Off" light that I was experiencing, an Innova 3100 OBD-II code reader says "No Powertrain DTC's or Freeze Frame Data is presently stored in the vehicle's computer" ??, and the CEL has disappeared? I expect that it may return next time I make a long drive. I read that the flashing overdrive "Off" light on the shift lever is indicative of a transmission problem?, but I'm still thinking that it might have been sticking vanes in the turbo since there seemed to be lower power when starting up from a stop.