thicker oil?

Motal 5100 ok to use on the zx12r??...reckon this bloody knocking(sounds bottom end) noise
could be oil too thin esp with this heat????? last oil and filter change abt 3 months ago...found out mech used synthetic oil used am i better off have 5100 being a thicker oil as the old girl now over 100000ks..any feedback much appreciated...hoping the prob could be that simple..or maybe i am just kidding myself..just trying to elminate the prob b4 l start spending the big bucks$$$$ Any suggestions would be much appreciated.
Cheers





Cheers

