5.4 L 175000 miles. blue smoke on start up, uses approx. a quart a month. probable causes?

 

A quart per month translates into a quart in how many miles? Blue smoke is indicative of oil in the fuel air mix. In your case it is most likely the valve guides and or valve seals that are allowing enough oil to seep into the combustion chamber while the vehicle is sitting to be noticeable in the exhaust at start up. Could be where the rest of the oil is being consumed also in small enough amounts per combustion event that it is not noticeable while driving.

 

First thing to do is to buy a Motorcraft PCV and replace the one it has. I'm assuming it has one. Why don't people tell us more about the vehicle for which they are asking for help? The aftermarket PCVs don't work well.

 

PCV ?? It is 01 f150 Lariat supercab 5.4l triton

 

PCV valve.

 

Sounds like valve seals or guides to me, too. I would start with the PCV because it is routine maintenance, cheaper and easier.

 

Ding, ding ding! We have a winner! Blue smoke, primarily at startup, is a classic sign of bad valve seals. Besides normal wear, the "rubber" seals in an engine all start to harden with age at about 8 to 10 years and hence start leaking. Oil puddles around the valve guides when an engine is off and when you first start the engine the vacuum on the intake cycle will draw the oil directly into the combustion chambers if the valve guide seals are leaky. After a couple of seconds the collected oil is gone and the the blue smoke stops. I'll BET that if you pull the spark plugs you'll find signs of burnt oil on them. I'll also bet that you have oil leaks on the front and rear crankshaft seals and at the oil pan gasket.