exhaust smoke on 1996 Lexus ES300

After stoping from a highway run such as a rest area stop.
When I start the car I get a hudge cloud of white smoke.
This happens after highway runs and after the car sits for a short time.
If I come off the highway and go home and the car sits overnight I get the same problem.
I have used a crank case cleaning flush several times with no change.
Was thinking it may be valve guide seals but I think that should smoke after sitting all the time and also would be blue smoke?
Anybody have any thoughts?
Don B.

Asked by for the 1996 Lexus ES300
You are right the smoke should be blue but it sounds like valve guide seals or worn guides which I have seen on higher mileage ES300 or ES300 that had infrequent oil changes. This engine is not prone to blown head gaskets as was the ES250. The most accurate way to test for a blown head gasket on a gasoline engine is to test for the presence of carbon monoxide in the cooling system. Snap-On, Matco (part # CO 2000), and Napa sell a tool to check to carry out this test. Another link to a supplier of this tool is Carbon Monoxide is only present if there is a blown head gasket or cracked cylinder head. I think the Napa part number 700-1006. . Signs of a blown head gasket are coolant loss (frequently have to top up the coolant level of the engine without seeing an obvious leak), experiencing over heating or rough engine running or the presence of white sweet smelling steam from the exhaust. A badly blown head gasket may allow engine coolant and oil to mix.
I have 145,000 miles on car.
I have owned it since 73,000 and change oil every 3000 miles
Have seen no loss of cooling fluid