Grease, by National Touring Musicals. Academy for Performing Arts, Lyric Theatre. March 26-28. FOR those who grew up in the 70s and 80s, songs like Summer Nights and Grease Lightnin' have been etched into their collective unconscious, just waiting for an opportunity to re-emerge. Audiences are now being given a chance to celebrate the youthful energy of 50s America - bobby socks, rock 'n' roll and drive-in movies - with the Jeffrey Moss production of Grease at the APA this week. To many people Grease is synonymous with John Travolta and Olivia Newton-John and it is sometimes forgotten that this musical started life on the stage. The story is straightforward enough: new girl in town meets boy, girl falls for boy. The girl is blonde, wholesome as cherry pie and ''Doris Day'' and the boy is tall, dark and a bit of a rogue. But it appealed to young people when it was first performed in the 70s because of its simple moral, ''there is no virtue in virtue''. Thus we see our heroine, Sandra Dee transformed from a ''goody-goody'' into a cigarette-smoking, wild sex kitten in five-inch stilettoes. In the process, she gets her man. Despite the obvious competence and talent of the cast, the production doesn't quite succeed. It is billed as ''Broadway's happiest musical'' but on the stage of the Lyric Theatre, it's a mediocre affair with few surprises. Grease is a combination of music, angst, love and comedy. All these elements are present in the performance but they do not always hang together to give a cohesive whole. Where they did the results were pleasing. There is a delightful scene in the secondact featuring a dream-like ''guardian angel'' complete with shiny white bell-bottom suit and blonde quiff. It's deliciously kitsch, funny and well-executed. This is a strangely egalitarian production in that it is sometimes hard to distinguish between the lead characters and the supporting cast, and this perhaps is a credit to the supporters. However, the leads are a weak point of the production. Tamar Kummel, as Sandy, is convincing as the ultimate good girl but we do not sense the underlying frustrations which motivate her metamorphosis at the end of the show, while Jeff Bodnar lacks charisma as the smart-talking and worldly-wise Danny Zuko. Although Zuko postures and cracks jokes, he does mock the macho image he portrays and is more a figure of comedy than an object of female desire. In the end, there appears to be more tension between the characters Rizzo and Kenickie than between the romantic leads. Maybe this will improve as the company settle into their performances at the Lyric Theatre and their stay in the territory.