Filtering the pump oil for the freeze dryer. 
Discussion
I’ve never thought of doing that with oil. How effective is that? For, let’s say, cooking oil?
I haven't tried it, but I imagine it would.
Is that a Britta water filter or something that comes with the freeze dryer? I read about filtering the oil of buying the optional higher priced oil-free pump. Looks pretty easy?
It is a Brita as far as i can tell. It came with the machine, but I think any would work. I am happy I went with this one instead of the other on.