what nerve agent is very oily and will stay active in an area for several days?

The nerve agent known for its oily consistency and prolonged activity in an area is VX. It is a highly toxic organophosphorus compound that can persist in the environment due to its stability and resistance to degradation. VX can remain effective on surfaces for days, posing significant risks in contaminated areas. Its use is strictly controlled under the Chemical Weapons Convention due to its lethal properties.