I've never been attracted to Zac!

He makes teen girls' hearts pitter-patter across the country, but Zac Efron just doesn't do it for his High School Musicalco-star Ashley Tisdale.

"I've never been attracted to Zac, and he's never been attracted to me - which is even more amazing! Ha!" she says in November's Seventeen.

"He always says I look hot, and I'm like, 'Aw, thanks Zac,'" Tisdale, 23, adds. "But really, it's more like siblings than a flirty relationship - he's seriously like my brother."

She says often turns to Efron - who is dating costarVanessa Hudgens - for advice.

"It's cool to have someone who's completely honest with you, who can give you a guy's opinion," she says. "And if I have a problem, I know I can call him whenever."