I believe it to be a primarily PE and or TMP ester with some PAO, more or less a trisynthetic blended oil heavy on the ester.
About two years ago the 3/30 5/30 5/50 and the 15/50 recieved an upgrade of the additive package that looks much like the package in the 0/20 Synergyn over in the VOA section here on this site .