Oil filler tube/ AOS - questions ??
 

I saw a thin film of oil around my oil filler tube next to the AOS but the AOS and everywhere else is dry. Should I replace the oil filler tube? I didn't see any cracks or loose hose clamp and AOS is dry. Filler tube looks like an inferior plastic tube.

Also, the car gives out a small puff of smoke every now and then (may be once every 2-3 weeks) at start-up. I assume that's normal for horizontal engine but how do you know if the AOS is beginning to get bad. I know when it is bad, you get lots of smoke at start-up but I want to replace at the slightest sign of problem and I am trying to figure out when. Should I pull out the AOS and check for any oil residue? Car is 2002 base with 49K miles. Thanks for your help!!