this is encouraging!

You just brought is back to STEAM on start-up.

Have you ever noticed steam/smoke coming from the tail pipe of cars pulling
out of a neighborhood in the morning as you drive past on the artery
street/road? This is normal, and by your first post, I think this is what is
coming from your Expedition.

Your Expedition has either the 4.6L or the 5.4L motor, and according to the
data I have are the same motor with different stroke. (the diameter of the
bore is the same, so the difference in displacement has to come from
stroke.) I am new to this power plant, and I've not heard that there is any
problem associated with valve seals. Your mechanic appears to hold the same
knowledge.

i just spoke with the actual technician how will keep the car overnight
sometime next week and do what he can to diagnose my problem.
During our conversation he these cars don't have Valve Stem Seal problems,
that the PCV Valves never go bad and if there was a hole in the Head Gasket
he would have noticed it last week when he had 20 lbs. of pressure on the
cooling system for 8 hours.
so i think leaving it with him overnight, with my figures crossed, is the
next step to take.
let you know what happens late next week.

thanks for your help!

You seem convinced you have bad valve seals, if you are correct, you need to
replace them.

If you have bad valve seals, you should notice oil consumption over time.

White smoke at start up is really steam, and is normal.

Sorry, What should I DO in a case like this?

THESE ARE MY Symptoms:
Bluish/White Smoke from tailpipe at startup.

"bad valve stem seals" Symptom  Definition:
The classic symptom of bad valve stem seals is, if when starting the car,
after it has set for a little while (say over night), clouds of smoke appear
from the exhaust and then stops after a few seconds. What happens is, while
the car is setting, oil leaks down the valve stem past the seal and
accumulates in the cylinder chamber. When you start the car, that oil is
burned off out the exhaust pipe.

SMOKE or STEAM?

If the latter, I suggest there is no problem at all.

Symptoms:
The classic symptom of bad valve stem seals is, if when starting the car,
after it has set for a little while (say over night), clouds of smoke appear
from the exhaust and then stops after a few seconds. What happens is, while
the car is setting, oil leaks down the valve stem past the seal and
accumulates in the cylinder chamber. When you start the car, that oil is
burned off out the exhaust pipe.

Bluish/White Smoke from tailpipe at startup.

What should in a case like this?