See, now you have me extending this oil thread but I'm too OCD...:grin2:
As I posted earlier, people are going to use what they want and while I am aware that SN includes "emission systems" elements, I still see no reason of using T6. The manufacturer does not recommend it, the owners manual does not recommend it, and the only reason I have read for selecting T6 is that it is generally cheaper than motorcycle specific oil. Granted, the owners manual is more of a "suggestion" manual for many as they treat some requirements listed in the book as though they are written in stone but when it comes to something like required oil the manual no longer applies.
I spoke with Chris today from the Motorcycle Division America Honda (866) 784-1870 and he confirmed my issues with using T6 in the 2018 GW. He advised me that if any problem occurs with the engine or it's components while using T6 oil and the oil can be determined in any way as a possible causation, the warrantee will be voided and all repair costs will be the responsibility of the owner.
Now I already know the next comment to be posted...I have xxx miles on T6 and I have never had an issue...Great, again your bike and your decision. I would still argue that the only oil that should be used in the bike should be whatever oil you want that meets or exceeds all requirements and any oil that does not meet this criteria should not be recommended to others who are looking for information on what oil they should use.