An apparatus and a process for recycling used engine coolant employs a reverse osmosis process for separating ethylene glycol from a concentrate coolant solution. The engine coolant concentrate is pre-filtered through a series of filters and pressurized prior to being passed through a semi-permeable membrane. The membrane separates the feed stream into a permeate solution of ethylene glycol and water and a concentrate solution. The concentrate solution is returned to a concentrate tank for continuous circulation through the apparatus. A heat exchanger maintains the temperature of the concentrate solution below a pre-established threshold.