Just remove the sub-pan. The oil sender does push inward and there is an o-ring seal.

When you say sub-pan do you mean steel oil pan or the cast aluminum part bolted to the bottom of the block?

Replacing block feed thru.
 

What is involved the electrical feed thru that make the connection for the low oil sensor on the 420sel V8 engines?

It looks like the pass thru element probably has an O ring and it is leaking oil. It also looks like it must be removed from inside the crankcase. Can it be done by simply removing the oil pan? What will I find on the inside?

I would like specifics before I open it up.