Printers, methods, and apparatus to filter imaging oil are disclosed. An example apparatus to filter imaging oil, includes adjacent electrodes and a switching circuit. The example switching circuit selectively generates an electrostatic field between the adjacent electrodes to cause particles suspended in the imaging oil between the adjacent electrodes to adhere to at least one of the adjacent electrodes, and generates an alternating electric field between the adjacent electrodes to cause the particles to be detached from the adjacent electrodes.