I drained the coolant, removed the thermostat and replaced the housing with just the gasket from the thermostat. Then I ran with the Steal Seal and distilled water as recommended for 1/2 hour, then letting the engine cool and repeating. Then I drained the Steal Seal and will replace the thermostat and put in new green coolant at 50/50 mix.
I did purchase a new housing and thermostat, but so far I don't think I will need it, unless I break something on the next R&R. It is fun get that thing out of there.
While the thermostat housing is out I need to replace the PCV hose, which has a gaping hole in it behind the motor. Then I'll replace the thermo housing and tube and refill.
I did the fuel filter today as well.
Time will tell on the sealer. If I see anything on inspection or any side effects from the sealer I will post again.
Thanks for the help.
Learning more and more about the Focus every day.