Mineral oil distillates having an aromatics content of less than 21% by weight, a water content of less than 150 ppm and a conductivity of at least 50 pS/m, and comprising from 0.1 to 200 ppm of at least one alkylphenol-aldehyde resin (constituent I) which includes a structural element of the formula in which R5 is C1-C200-alkyl or C2-C200-alkenyl, O—R6 or O—C(O)—R6, R6 is C1-C200-alkyl or C2-C200-alkenyl and n is from 2 to 100, and from 0.1 to 200 ppm of at least one polar oil-soluble nitrogen compound (constituent II), excluding those mineral oil distillates in which between 0.001 and 10 ppm of an oil-soluble, organic sulfonic acid-ammonium salt are present.