>    So, with a properly located swirl pot, one fills to about
> 1 - 2" below the cap, just as with an older (1950's) automobile
> radiator.  Right?
Right. If you fill the swirl pot to the top (as I did) you don't get to see
any anomalies  in the cooling system behavior. Sounds like a "best practice"
to me.
John (checking the weather for an evening flight)