Forever 'Grease' Sure, The Actors Were Too Old To Play Teenagers, And The Message It Sent To Young Girls Was Questionable. But 20 Years Later, It's As Popular As Ever.

NEW YORK — Grease, the most successful movie musical of all time. Grease, a rockin', rollin' celebration of everybody's high school days as performed by a bunch of actors who hadn't seen the inside of a high school in a decade. Grease, a movie with a moral: Act like a tramp, and you'll get the guy.

Olivia Newton-John, looking almost as sweet and goody-two-shoes as the sweet, goody-two-shoes Sandy Olson she played 20 years ago, laughs.

``Since I've become a mother, I really do question that message,'' says the soft-spoken singer, the parent of a 12-year-old girl. ``When we were making Grease, it didn't seem terribly important - it wasn't a serious movie. But when you become a mom and then your children watch it, what kind of message are we giving young girls?''

Easy. Transform yourself from a ``wholesome and pure,'' ponytailed cheerleader into a teased-hair, teetering-on-high-heels babe in skintight black, and John Travolta can be yours.

But Newton-John, sitting in a hotel room not long ago to talk up the big-deal anniversary rerelease of Grease (it opened everywhere on Friday), says that maybe the message goes a little deeper than that. After all, Danny Zuko - the dimple-chinned greaser played by Travolta - transforms himself, albeit fleetingly, too: He pulls a white Rydell High letter sweater on over his sleeveless black T in the movie's climactic carnival scene.

``If you really look beneath,'' suggests Newton-John, 49, ``you can see that they were both trying to change for each other. It was really peer pressure, what their friends thought, or what they thought they should be for the other one. And basically, they just cared about each other.

``But it's a strange thing, that legacy: Put on tight pants and you get him.''

It's also a strange thing that three months shy of its 20th anniversary - Grease debuted the same weekend as Jaws II on June 16, 1978 - people are still talking about this thing. Made for $6 million by a first-time director, Randal Kleiser, and a producer, Allan Carr, whose sole previous film was a dubbed U.S. version of a Mexican cannibalism pic, Survive!, the film has earned $360 million in global receipts. It has sold more than 8 million soundtrack albums.