Tomorrow night - and every Saturday night, for awhile at least - you have 2, two, TWO! great options for oldies (depending on your definition of "oldies") on the AM dial (which is the way to hear oldies, I'd say. At least it's the authentic way).
On WNYC-AM 820, between 8 and 10 pm Saturdays, you can hear Danny Stiles classily present his Big Band Sounds show. Danny plays music from the 20's through the '50s - not exclusively Big Band, mind you, just classic inventive American Tin Pan Alley pop you'll hear nowhere else. Danny's got an amazing collection of music (most of it on the original vinyl) and an incredible knowledge about the singers, the songs and the songwriters. There's nothing like driving around on a Saturday night, with Danny on the radio, pretending - for a moment - you're on your way to a glamorous nightclub, partying like it's 1939.
For oldies of a more recent vintage (i.e. stuff that I remember from my childhood) it warms the heart that 77 WABC is playing an oldies format on Saturday nights from 6-10 pm. Deejay Mark Simone plays old WABC soundchecks and jingles amidst the hits. There's even a Message Board dedicated to it. Rock on!