| abstract |
Lubricating oil composition comprising a mixture of: (A) a hydrocarbon as a low-viscosity constituent, (B) a polyalkylene glycol (PAG) as a high-viscosity constituent wherein the oxygen/carbon weight ratio is in the range of from 0.450 to 0.580, and (C) a compound as a control constituent wherein the oxygen/carbon weight ratio is in the range of from 0.080 to 0.350. The present invention offers offer a lubricating composition which has two constituents, a low-viscosity constituent together with a high-viscosity constituent which is capable of phase separation from the low- viscosity constituent at low temperatures, and which becomes uniform at high temperatures. By using a control constituent, it is possible both to control appropriately the separation temperature of the lubricating oil composition which is in the form of a mixture of two constituents, and to maintain the kinematic viscosity at high temperatures at almost the same level as when not using the control constituent. Given that the low- viscosity constituent functions at low temperatures and that at high temperatures the lubricating oil functions with a viscosity enhanced by mixing of the high-viscosity constituent and the low-viscosity constituent, it is possible to use such a lubricating oil composition over a wide range of temperatures. |