Abstract: There is disclosed a lubricating oil for internal combustion engine which comprises:a mineral oil and/or a synthetic lubricating oil as a base oil, and oxymolybdenum dithiocarbamate sulfide expressed by the chemical formula (1): ##STR1## wherein R.sub.1 or R.sub.1 and R.sub.3 denote a branched aliphatic hydrocarbon group having not less than fourteen carbons, and R.sub.2 through R.sub.4 or R.sub.2 and R.sub.4 denote an aliphatic hydrocarbon group having not less than four carbons, in the amount of 0.005 to 0.2% by weight, when calculated as molybdenum (Mo).

Abstract: An apparatus for detecting the deterioration of an engine oil including a ceramic heater radiating infrared light including infrared radiation having a wavelength of 6.1 micron meters which is equal to the specific infrared absorption peak of ester of nitric acid contained in the engine oil. The infrared light is made incident upon a photodetector via a band pass filter having a center wavelength of 6.1 micron meters to detect an amount of the ester of nitric acid contained in the engine oil. It has been experimentally confirmed that an amount of the ester of nitric acid is proportional to the total acid value which is a measure of the deterioration of the engine oil, so that by suitably processing an output signal of the photodetector, it is possible to detect the deterioration of the engine oil. The thus detected deterioration may be displayed on a display device provided on a front pedal of a car.

Abstract: A lubricating oil composition for the internal combustion engine comprising (i) a mineral lubricating base oil, a synthetic lubricating base oil or a mixture thereof, (ii) a specified amount of at least one alkyl molybdenum dithiophosphate having secondary alkyl ##STR1## wherein R.sub.1 is a secondary alkyl group having from 5 to 8 carbon atoms, X is O or S which may be the same or different, and the O/S ratio is from 3/1 to 1/3, and (iii) a specified amount of at least one alkyl zinc dithiophosphate having a primary alkyl group represented by the formula (II) ##STR2## wherein R.sub.2 and R.sub.3 are each a primary alkyl group having from 3 to 8 carbon atoms which may be the same or different, and (iv) an additive of the lubricating oil containing the above components (b) and (c) for use in internal combustion engines.

Abstract: A lubricating oil for diesel engines is disclosed. This oil is based on a mixture of lubricating mineral base oil and a highly aromatic light base oil, and is highly effective in reducing the wear of the diesel engine designed to run with heavy fuels having high carbon to hydrogen ratios. The oil is also advantageous in that it does not clog the lubricant filter.