everytime to change my oil ( mobil 1 5w-30 ) about every 4k, i notice white milky skin on the fill cap, but i do not lose any antifreeze i think, and the oil is not milky, just dark brown like normal, should i be concerned about this? or just possible bad pcv? BTW this is a 2000 f150 with a 5.4 and 134k mi.

 

no need to worry, thats just condensation that builds up on the underside of the cap. its completely normal to see that, just wipe it off!

 

Too many short trips don't let the oil get hot enough to burn off any condensation. You need to take it out and drive it for a couple of hrs.