We generally choose to use water bourne stains and finishes instead of petroleum based products because of their relatively lower toxicity and impact on the environment.  Water bourne stains and finishes are porous and allow your logs to breathe rather than sealing in residual moisture which can lead to rot.  A high quality stain will protect your logs from discoloration and fading due to the sun’s ultraviolet rays.  A good clear coat will protect from moisture without gunking up your logs.  When you live in a house made of trees it’s good to be able to feel the wood!