Zac Efron -- I Needed a 'Social Lubricant'

Zac Efron is publicly acknowledging his struggle with addiction ... and he chose to make the revelation deep in the wilderness with Bear Grylls.

Zac doesn't mention any drug or drink by name ... we broke the story he had 2 stints in rehab last year for cocaine and Molly.

The actor says it became impossible to go out in the world because, as he put it, the press followed him everywhere. So he needed what he called a "social lubricant" to muster the courage to venture outside his house.

You gotta hear Zac talk about his problem and how he's now put it in check. It's interesting.