I asked Robinson and just got the following reply-
Page 3 of Lycoming Service Instruction 1070S dated 24 April 2013 cautions
the operator to ensure "...Lycoming oil additive LW-16702, or an equivalent
finished product such as Aeroshell 15w50, must be used." Link:
http://www.lycoming.com/Lycoming/SUP.../ServiceInstru
ctions.aspx
If you look up Aeroshell 15w50 it says that the Lycoming LW-16702 is already added to it in manufacture. So I guess that is the answer to the original question.