This paper presents the failure analyses of an industrial lubricant used for heavy construction equipments and an accelerated life test for the occurrence of sludge. Failure modes and mechanisms of the lubricant are analyzed from field test sample. For typical failure mode `sludge`, an accelerated life test is performed at higher than usual temperatures. Activation energy, acceleration factor, and equivalent lubricant temperature corresponding to field use are estimated by assuming Weibull lifetime distribution and Arrhenius life-stress relationship and by using Wei-Bayes approach.