from what i have gathered, synthetic is always superior to other oil. so no problem switching. hi mileage dictates better oil of same weight and viscosity as manufacturer recommends. Dont think it will clean up sludge, 100 k if maintained there would not be any sludge probably, u may think about a HD high detergent oil to clean engine out if proven to have buildup of sludge but ask dealer about this. My personal opinion.