I searched this site for "oil trap box" and this is the only one I
found for 800 series:

http://www.brickboard.com/AWD/?id=136187

If it is what I think it is (based on the description)
then it is pretty easy to get at. The above posts seems to have a
description of the same steps at Bay 13 for cleaning the flame
trap. The Bay 13 site has this text under one of the photos:

The "Flame Trap" is inside the connector and this one has a lot of oil and crud built up, if you can't pull it out with needle nose pliers or something similar, then screw, a small screw into the center of the flame trap and use that to tug on to get it out.

I think the "oil trap box" is just the connector that they mention as
having a lot of oil and crud built up (it holds the flame trap -- a very
small plastic disk with holes in it). The picture above the text at
Bay 13 shows it and you can barely see the holes (the part is actually white
when cleaned).

Cleaning this area is known to help prevent probelms with the rear main
seal and allow the engine to vent correctly. Posts about the "oil trap box" that I found also were dealing with this area. So, I think the flame trap
and associated connector are what is meant when the phrase "oil trap box" is used for the 800 series.