Doverlube NCEP contains no chlorine, sulfur, or phosphorous.  It has been found to work very well on hard-to-machine metal alloys such as titanium and stainless steel.  It is a fully reacted material which exhibits both boundary lubrication and extreme pressure characteristics.  The added benefit of a fatty component not only improves metal wetting, but facilitates the contact between the metal surface and the extreme pressure portion of the additive.  
Doverlube NCEP is also non-corrosive and low in toxicity.