Electrostatic oil cleaner systems use electrostatic precipitation to remove sub-micron particle of insoluble material, without affecting soluble oil additives. Tiny particles are electrostatically driven to and captured on positively or negatively charged walls of electrodes. Large particles are trapped in the resin impregnated cellulose filter. Coalescing filter in dehydration cell is used for removal of moisturewater up to 5000 PPM. Modern additives-treated oil is highly resistant to deterioration; it can continue service indefinitely if kept clean and contamination free.