Oil deterioration suppressing apparatus for internal combustion engine

An oil deterioration suppressing apparatus for an internal combustion engine, comprising a first oil filter and a second oil filter, wherein the first oil filter comprises a first filter member for filtering oil from an oil pan in which oil is stored, and the second oil filter comprises a second filter member for filtering oil from the oil pan, and wherein the second filter member is made of a ceramic material and has a mean pore size smaller than the mean pore size of the first filter member,

• wherein the first oil filter is a full flow filter which is connected to a downstream side of the oil pan in oil flow and an upstream side of lubricated parts of the internal combustion engine in oil flow and which filters the oil supplied to the lubricated parts of the internal combustion engine, and wherein the oil deterioration suppressing apparatus has a bypass route which is branched off at an upstream side or downstream side of the first oil filter in the oil flow direction and communicates with the oil pan, and the second oil filter is a bypass filter which is placed in the bypass route and filters the oil toward the oil pan.