Have you noticed that the older you get, the newer the oldies on the radio become?

If you're in your sixties, your oldies are Elvis and doo-wop. If you're in your fifties, your oldies are Motown and "Downtown." If you're in your forties, your oldies are, well, they're all over the board -- anything from folk-rock to disco to the hard stuff. Therein lies the problem facing hundreds of oldies radio stations, including Washington's WBIG.

It no longer makes commercial sense for oldies stations to play more than an occasional, token record from the 1950s because no one in radio's target audience remembers those songs from his or her youth. Increasingly, audience surveys show that those who listen to oldies stations don't want to hear much from the early '60s, either.

So aside from the Beatles, what can oldies stations play and still hope to win a mass audience of listeners now in their thirties and forties?

Consultants who advise oldies programmers have been pushing them gently into the '70s music library, but it's a dangerous road because that's when Top 40 radio died and all manner of much more specialized formats came along. So most Americans from that era grew up listening only to the kind of music they liked -- the soft soul of the Stylistics and the Spinners, disco, hard rock, lite rock and so on. The result was the same kind of polarization the nation is now experiencing in its politics.

Oldies stations are leery of cobbling together those tastes in one station. But by testing audience appetites for inoffensive songs of the '70s, they've identified some tunes that reach across musical boundaries (Rod Stewart's "Young Turks," any of Fleetwood Mac's hits). And over the past three years, that has permitted oldies stations to slowly push the average year of songs they play from mid-1965 to almost 1967.

Ever eager to quantify musical tastes, a major consultant to oldies stations, Coleman Research, has advised programmers to use a mix of music with "between 17 and 18 percent '70s content."

But what if you love the really old stuff? Fear not: A new format is born. ABC Radio this spring launched its True Oldies Channel, a format focusing on the years 1958 to 1964. The programming is being offered primarily to stations on the AM band, where music has been dying off for decades because of the far better sound quality on FM. But the great hits of the early rock era were recorded in monaural sound, for which AM radio should suffice.

Starting in Cincinnati last year, several "real oldies" stations have popped up on AM, bringing back local hero DJs from the '60s and re-creating the stations that originally played Chubby Checker, Connie Francis, the Four Seasons, Elvis, Chuck Berry and so on. Does this mean the return of Washington Top 40 stations such as WOOK and WEAM? Stand by.

Elvis and his ilk are centerpieces of ABC Radio's True Oldies Channel, focusing on the years 1958 to 1964.