You could use a trap to avoid that oil getting into yout product.
The whole idea is to maintain a (slight) N2 pressure in your system to avoid any air or moisture getting into it. When I worked with organo metal compounds in college I used a simple fermentation bubbler (like this https://images-na.ssl-images-amazon.com/images/I/61LBAdkqkUL._AC_SY879_.jpg) and had one bubble of N2 come through every second or two
