Top Five Car Engine Problems Explained

PROBLEM No. 5. THERMAL-OXIDATIVE STABILITY OF THE MOTOR OIL

Question: What is the thermal-oxidative stability of the motor oil? 

Reference of MITASU OIL expert: The motor oil ability to resist to oxidation at the engine operation is called thermal-oxidative stability. The main reason of oxidation is high temperatures in the engine. 

Question: What temperatures are concerned? 

Reference of MITASU OIL expert: The temperature, at which the motor oil operates in specific areas achieves and exceeds 200 °С. At such a high temperature the processes of any hydrocarbon oxidation are very active. In the areas of the piston rings, valve guides, on the surface of the pistons and cylinders, in the gaps of the bearings the oil is in the form of thin films on hot metal surfaces.  All this creates exclusively favorable conditions for its oxidation and oxidative polymerization. 

Question: What impact has this oxidative film on the engine parts on the engine operation? 

Reference of MITASU OIL expert: Indeed, one of the forms of demonstration of the thermal-oxidative processes in oil is formation of thin lacquers on the parts with the high temperature. The lacquer film thickness can be from the micron fractions to 100–200 μm. The lacquer formation deteriorates the thermal conductivity of the parts and causes their overheat and as a result, scuffing of the cylinder and jamming of the piston rings and sometimes of the piston itself.  The lacquer film is held tight on the parts and does not solute in the strongest solvents. 

Question: How one can decrease the value of the oxidative lacquer film? 

Reference of MITASU OIL expert: In practice, the sole way of action on the thermal-oxidative stability is the correct choice of basic oils including the minimum quantity of easily boiling fractions and having, maybe, a narrower fractional composition. Such oils include high-quality oil used in products of MITASU OIL CORPORATION, Japan. Their evaporability and oxidizability are less severalfold than of their analogues. This creates the favorable conditions for MITASU OIL motor oil operation in high-temperature areas of the combustion engine.