07 6 with 3 liter, 80k. oil changed every 3k by me(motorcraft semi synthetic 5w20) for the last week or so when the engine is cold there is a ticking noise like something is going on with a lifter. no engine codes and it lasts about 5 minutes. any ideas?

 

car spent two days at a reputable mechanic...he hears the noise but has no clue what it is. he thinks valvetrain related but not sure enough to dig into it.