Marine crankcase lubricant

A crankcase lubricating oil composition having a Total Base Number ranging from about 3 to 10 comprising a major proportion of a mineral lubricating oil containing from about 1 to 5 weight percent of at least one overbased salt selected from the group consisting of calcium alkylphenolate, sulfurized calcium alkylphenolate and mixtures thereof, from about 0.1 to 1 weight percent of a zinc dithiophosphate represented by the formula:

• ##STR19## in which R is a hydrocarbyl radical or a hydroxy substituted hydrocarbyl radical having from 3 to 12 carbon atoms, from about 0.05 to 1 weight percent of an ethoxylated alkylphenol represented by the formula:
• ##STR20## wherein R represents an alkyl radical having from 4 to 20 carbon atoms and n has an average value ranging from about 4 to about 30 and, from about 0.2 to 5 weight percent of a N-alkylglycine derivative selected from the group consisting of:
• ##STR21## in which R is a hydrocarbyl radical having from about 10 to 25 carbon atoms, R' represents hydrogen or an alkyl, hydroxyalkyl or an aminoalkyl radical having from 1 to 5 carbon atoms and R" represents an alkyl or hydroxyalkyl radical having from 1 to 5 carbon atoms or a --CH.sub.2 --CH.sub.2 --NH).sub.x H radical in which x has a value from 1 to 3, and ##STR22## in which X represents an oxygen atom or a divalent N--R' radical and R and R' have the values noted above.