Another Disney Star ... another substance abuse arrest .... "Lab Rats" star Billy Unger has been arrested for DUI.
The 18-year-old was driving on Pacific Coast Highway in Malibu Saturday just after midnight when Sheriff's deputies pulled him over for speeding.
Deputies suspected Unger was under the influence. He blew a .08 -- barely the legal limit, but there's a special California law for drivers under the age of 21. If they have ANY alcohol in their system it's considered driving under the influence.
Unger was arrested, taken to jail and released.
Unger is now on a fairly long list of Disney stars with drug and alcohol problems. Others include Zac Efron, Mitchel Musso, Jake T. Austin, Orlando Brown, Kirsten Storms, Christina Aguilera, Britney Spears, Shia LaBeouf, and of course ... Lindsay Lohan.
7:45 PM PT -- Billy issued a statement to TMZ thanking his fans for their support.