I use lanolin based CRC LanoCote Natural grease.

The CRC website states LanoCote is "an environmentally friendly product which exhibits superior corrosion protection and anti-seize properties. It offers outstanding, long-lasting protection in harsh conditions without compromising treated materials or harming the environment.

Blended from lanolin, CRC LanoCote is non-toxic, non-carcinogenic and biodegradable.

Lanolin is naturally hydrophobic (water-repellant) and due to its affinity to metals, CRC LanoCote forms a highly effective moisture barrier on surfaces, stays flexible and does not dry out or wash off."

It is good stuff, I can highly recommend it.