I've tried it all and had probs still. Here's a do-it-once and NEVER have to bleed your system again!
-Pull out thermostat
-Drill a 1/4" hole or two on the flat part (let's air escape the system)
-Clean off thermostat
-Put thermostat in pot and make sure it opens at the correct temp
-Install thermostat using RTV or gasket, whichever works for you
End Result
System will always self bleed and will never have to worry about this again, regardless of how many times you drain and fill the coolant!
Just my .02 as I've drained and refilled my coolant about 25 times and this was a solution I would have paid $100 for.