Except, then you are running the risk of premature wear to other parts, sliding surfaces that are not getting adequate lubrication for maby only a milla-second or maby a Second or two! Oh, no,...especially if there are Gut-n-Tight clearances for everything else, like there would, or should be in a Japanese motor. Then alleviating Piston Slap with Thicker oil would actually be Slowly killing the motor. Of course, everything like climate, driving distance, driving style, etc have a Major impact as well, and a thicker oil for start-up Cold Piston Slap might not make a bit of differance to anything at all, but that.