Engine lubricating oil replacement timing monitoring system and method for an automotive vehicle

An engine lubricating oil replacement timing monitoring system for an automotive vehicle which indicates to a vehicle occupant the end of service life of the engine lubricating oil, comprising:

• (a) a first sensor which detects the engine speed (n);
• (b) a second sensor which detects the load on the engine (L);
• (c) a calculating means which calculates the amount of soot (T) presently contained in the engine lubricating oil from the detected values of said first and second sensors;
• (d) a memory means which receives and additively stores the calculated amount of soot in the engine lubricating oil from said calculating means so as to record the total amount of soot therein;
• (e) a judging means which judges whether the total amount of soot additively stored in said memory means arrives at a first predetermined amount (R), the first predetermined amount being a maximum allowable amount of soot suspended in the engine lubricating oil;
• and
• (f) an alarm unit which produces an alarm to the vehicle occupant when said judging means judges that the total amount of soot becomes equal to the first predetermined amount.