A mobile purification apparatus for purifying oil contaminated with grit, metal particles, water and the like. The apparatus includes a strainer with a filter cartridge for removal of large contaminant particle and a filter apparatus. The filter apparatus including a heater and an upper filter element section with a plurality of filter media layers therein. The filter media layers are supported by a screen and compressed by a biasing spring. A lever is provided for off-loading compression on the filter media layers so a top of the filter apparatus can be removed to allow for cleaning and replacement of the filter media layers.