Whitey is right, no negative implications about anything you(blackbird) said. You have no need to retract anything.
5W30 is often a oil that is energy conserving, as it states it on the back. Blackbird, you are right that it is thinner. The 10W40 and the 20W50 you used is likely not “energy conserving”.
This designation does not automatically make your clutch slip, but it means it is possible. I have experiemented and have had good success (without slippage) on some of my older bikes using 5W30, but because all clutches are made different, it just isn’t a good idea for me to recommend that to others.
Oil is oil, it lubes…carries away heat…is a protective film. Important but not magical. I won’t comment about the diesel oil as I have no experience with that personally.
This is a great forum, with good intelligent people. No need to bash anyone so please don’t take anything I said as negative. gdawgs.