Does a paladin turning undead use his paladin level or
his turning level (three below his paladin level) to see if he
destroys undead?
For all effects related to turning, a paladin is treated as a
cleric of three levels lower than her paladin level. To destroy a
2-HD zombie with a turn undead attempt, a paladin must be at
least 7th level (and thus effectively a 4th-level cleric).