[trosco]

Lower mechanical noise does not automatically convert to better lubrication of moving parts. Heavy oils (higher viscosities like 20w50 or straight 40W for example) are quieter because they "dead'en" sounds (another way to say they dampen the transmission of sound waves) not because they flow easily into the areas of engines and transmissions that move in conflicting directions. Those areas, like say a valve stem to a rocker arm, require lubrication and cushioning. You could put 4 quarts of 80w90 gear oil in your motor and it would be very quiet, but it would be very poorly lubricated in areas like rod bearings, piston wrist pins, cam bearings and etc. Use a oil weight and grade recommended by your manufacturer.