He has Asperger's, because he shows signs such as: His obsession with Propane and other interests. A bit uncomfortable with sexuality, and at times can be distant from his family. Prefer to not be very emotional, Hank can be very stoic.

What condition does Hank Hill have?

Hank suffers from a fictional genetic disorder called Diminished Gluteal Syndrome (DGS).

Is Dale Gribble a schizophrenic?

Dale presumably suffers from Paranoid Personality Disorder, although it is unknown how he acquired the disorder. Dale's mother is deceased, this fact being learned in the episode "Bobby on Track".