Those lines are both literally "drains" for oil return. If the grommets aren't severely cracked, sometimes just keeping them clean will help to slow the leaking of oil.

Also, both of the wikka links have great explantions. I will have to disagree with a couple of points in the installation of the lower grommet for the turbo drain. I tried it that way, twice, and split the brand new grommet both times. After reading several other posts on doing this job, I found out that the best method is to install the lower grommet, before the bottom o-ring, and slide it up the tube an inch or so. Once the tubes are installed, including bolting to the bottom of the turbo, slide the grommet down and press it into the oil pan. Silicone grease or KY gel works best for lubricating the rubber. Once the grommet is seated, clean the excess lube off with brake cleaner and give the grommet a shot of silicone spray.

Doing it this way is considerably easier and after 4 years has shown no signs of leaking.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )