Olivia Newton-John and John Travolta’s smash hit musical film “Grease” opened in theaters on June 16, 1978. The movie would go on to become one of the most popular movie musicals of all time.The film was Newton-John’s first major foray into acting and while speaking with Billboard after the film, she said it was a career changing opportunity. “Grease is the most important thing I’ve done. Because I was playing a role I was able to try something different (in terms of a more powerful singing style). I would have never dreamt of it if not for the part. It was an excuse to do it and it worked,” she recalled.The film was released to generally favorable reviews and also spawned a number-one hit song for the lead actors with “You’re The One That I Want.” That track was released as part of the official movie soundtrack and hit the top of the Billboard Hot 100 chart on June 10, 1978.