Engine oil

If you're interested in bio-engine oils, Renewable Lubricants seems to be discussed regularly on BITOG:
http://www.renewablelube.com/

More discussion of oil additives, specifically Lucas Zinc additive:
http://www.forabodiesonly.com/mopar/showthread.php?t=83428

SSDan has an excellent explanation of why adding a whole bottle is a bad idea. Too much ZDDP or Moly doesn't do your engine any favours. According to Widman (Corvair article), phosphorus levels over 1400 ppm (0.14%) can lead to increased engine deposits and levels over 2000 ppm (0.2%) can lead to camshaft spalling.

Pick an properly formulated oil for your engine and don't add anything else to the crankcase.

http://www.allpar.com/old/oils.php

ACCCC HDEO List