I prefer this definition from one of the online dictionaries.
Oldies is a generic term commonly used to describe a radio format that usually concentrates on Top 40 music from the '50s, '60s and '70s.Oldies are typically from R&B, pop and rock music genres. Country, jazz, classical music, and other formats are generally not considered oldies music, although some of those genres have their own oldies format.
Note that it says "Top 40", because a lot of rock from the mid 60s to late 70s would be considered, "Classic Rock". Also note that any music coming out of Motown during that period, is more likely to be called Motown, even though you could also call it Oldies. There is also some music made during this time period, that could be called Funk or classic R&B or even Disco. You can't just simply apply the term oldies to just any music from period. I would never consider any 80s music as Oldies. Most of the time, people refer to late 70s through 80s soul and dance music as "Old School". I think the easiest way to refer to music is to go by the decade and then apply the sub-category, like 80s metal, 80s rock, 80s pop, 80s R&B or 80s dance music. I think younger people care more about their labels than older people. People can't stand the fact that a lot of other people like their favorite music too, so they like to create all these sub-genres to convince themselves that their music is somehow different from the mainstream. Take a look at this list of some of th types of metal music.
heavy metal, thrash metal, speed metal death metal, black metal, power metal, doom metal and gothic metal, Alternative metal and Nu metal, post metal.
It's ridiculous. I think they should come up with one called, "No, you don't understand, see, I'm not like those all those people, I'm different" metal. It's not only happening in metal. It's starting to happen in rap and other genres. Way back when I cared about labels, we had rock, hard rock, pop, disco, soul/R&B, funk, punk, country, jazz and classical and that was almost all of it.