A multi-phase lubricant composition useful in a process for lubricating one or more operating components which are exposed to an operating condition change is described. Under a condition at which the lubricants are at least partially miscible, the phases combine to provide a lubricant having a physical property which is modified to be more appropriate for lubricating under the new condition, such as a higher viscosity. Typically the lubricants are at least partially miscible at an elevated temperature and at least partially immiscible at lower temperatures. A density difference between the phases is preferred for ease of separating the phases. The composition is preferably a combination of a hydrocarbon oil and a polyalkylene glycol such as polypropylene glycol.