Here's what is on the MMO board about this topic. My buddy AD asked the question, since he and I have been exchanging emails about it. Hopefully one of their tech guys weighs in.
One of our Bitog members posted this over on the MMO forum. I pasted this:
Also note that since I put this together, I have found out the Phosphorous is Tricresyl Phosphate, an organophosphate - a very, very good AW/EP additive.
See the link below for details:
http://en.wikipedia.org/wiki/Tricresyl_phosphate
There have been many studies on the effectiveness of TCP, and I have not found anything that surpasses it in EP friction reduction and anti-wear - and it is very complementary to ZDDP as it works in the higher temp range where ZDDP fails.
It is also very good at cleaning up varnish (in addition the to mineral spirits)
TCP is what gives MMO the lead scavenging, not the dichlorobenzenes. Also note the link below - that it is stated that the TCP (organophosphates) is the main ingredient that prevents corrosion from chlorinated hydrocarbons (dichlorobenzenes) as noted below.
“Oil-soluble organophosphates, with or without zinc, have excellent high-pressure and antiwear properties, and provide corrosion protection especially in presence of chlorinated hydrocarbons. ZDDP starts decomposing at 130-170 °C, while the activation temperature of TCP typically exceeds 200 °C. Their reaction products form a chemically bonded lubricating film on the surfaces.”
http://en.wikipedia.org/wiki/EP_additive
Also note that the version used today has reduced the “o-” part of the tricresyl to eliminate the neurotoxicity, otherwise it would have to be listed in the MSDS.