Bob,
PLEASE READ MY POST----------- It say's "From
ad for ZDDP Plus
Oil Additive:" This was found on their web site
MORE regarding EPA according again to ZDDPlus
www.zddplus.com
" As part of an effort to reduce vehicle emissions, the U.S. EPA offers vehicle manufacturers "credits" for early implementation as well as penalties for violation of emission reduction standards. The EPA's program called for 100,000-mile catalytic converter life by 2004, 120,000 miles by 2007, and 150,000 miles by 2009.
To achieve these goals, automotive manufacturers have pressured their oil suppliers to remove substances from motor oils that would shorten the service life, including the proven EP (extreme pressure) additive ZDDP (zinc dialkyldithiophosphate). Zinc and phosphorus from the ZDDP can be present in small amounts in the exhaust gas of an engine depending on the amount of
oil which is consumed in combustion. These elements can coat the catalyst reducing the amount of catalyst exposed to the exhaust gases, ultimately increasing emissions at the tailpipe. As a result of the EPA mandate, the ZDDP level in engine oils has been declining since the mid-1990s, roughly coinciding with the implementation of OBDII."
So it appears that the reduction in ZDDP is the result of the auto manufactures "mandate" by EPA to reduce emissions and not a direct mandate to the oil companies.
The more I read up on this topic the more questions seem to arrise. Do check out the link I provide above for some basic reference info. It appear's that bottom line is that oil
zinc levels have been reduced to help auto manufacturers meet EPA and that an addive is needed for older "flat tappet" engines to prevent premature engine ware. GM EOS and ZDDPlus appear to be additives to consider.
Mike