My old man owns the Petro Can marine in Hardy, been selling ob oil there for over 20yrs. Just asked him about this, he said he has had lengthy coversations with the lube department in Perto Can because guys had told him his oil didn't meet the standards that the Quicksilver and other oils did and they couldn't use it in their engines. He has since spoke will almost all OB manufacturers, Yamaha, Merc, Honda since a lot of them say you have to buy their oil during warranty years. Wrong, as long as you use TCW3 you are good.
The answer is, beside synthetic oils as long as it says TCW3 on you are going to go. This means it meets all requirements that outboards call for. Do not let anyone tell you different, you not need to buy the expensive stuff as it is all the same. He is will to answer any and all questions on this, call him at 250-949-9988, talk with Gord or Dale.
Hope this helps!