A lubricant’s purpose never changes -- turn stiff and rigid into loose and lithe. A lubricant’s form is variable, however. The lubricant of choice for tightly fit engine internals is assembly grease. The proper lubricant for a nervous, quiet friend is a shot of tequila. And the lubricant for the 2015 Subaru WRX is snow. A light dusting of snow turns every street into a low-mu surface, letting our 2015 Subaru WRX with its Michelin X-Ice Xi3 winter tires from Tire Rack loosen up and play like the stage-ready rally car it dreams of becoming.