Self - Gripping Oil Filter Wrench A self-gripping oil filter wrench is a type of tool designed to assist in the removal of oil filters from vehicles or machinery. It is also known as a self-adjusting oil filter wrench or a self-locking oil filter plier. This specialized tool is designed to grip and turn the oil filter for removal, and it's particularly useful when dealing with oil filters that are difficult to access or have become tightly stuck due to previous installations.