A lubricant formulation which is effective to remove or prevent carbon deposits in internal combustion engines has a solvency as defined by aniline point from about 20 to about 115, a volatility (as measured by NOACK) of less than 15%, an oxidative stability (as measured by PDSC) of above 40 minutes and a base oil viscosity of above 2 and below 10 cSt. The lubricant formulation can be formed from a blend of Group III, IV and V lubricants, in particularly polyalphaolefins, alkylated naphthalenes and polar Group V base stocks such as polyol esters. The carbon deposits can be removed from the engine piston by simply running the engine with the lubricant for one required cycle, or can be used continuously in the engine to prevent buildup.