I don’t think it’s oldies unless it’s your oldies, the music you remember from some long-ago period of life. Usually it’s high school and or college. Any other old music you listen to simply makes you a person of remarkably eclectic and receptive, yet discerning, tastes.
The music of my college years is usually denoted today by either “classic rock” and/or “disco”. I can scarcely abide classic rock as it is usually presented today by automated playlists that omit all the good album cuts. I do like a lot of older rock from the sixties, particularly the early psychedelic stuff and so called “garage rock”. Even though I was really just a kid, I suppose I have to admit that they are “my” oldies as well, because I was musically aware pretty early on. For example, I remember really liking the Beatles on Ed Sullivan, even though I was only six. I’ve liked the Doors since I first heard them at age nine.
Besides that, I like a wide variety of older music, ranging from jazz vocals to various incarnations of blues. Blues and jazz, for that matter, is a common thread through much of my musical life.
To be fair to Greenday, I don’t think there’s been a whole lot of change in rock music generally since they’ve been around. Although we’re talking about a twenty-year stretch of time, as I’ve always maintained here, there’s no way you could compare it to the twenty years that ended in, say, 1970.