No age limit as long as it's legal. She's mostly fucked guys her age or older but she was still regularly fucking guys as young as 18 in the military when she got out at 32.
We also had a couple in the apt next door that she was friendly with that consisted of a white woman in the army her age(33 or so) who had divorced her husband to shack up with a 19 year old black guy. He was quickly fucking her on our back porch every other night after his girlfriend fell asleep. We were in this early stage where I knew she was secretly fucking black guys, was turned on by it, and she knew I was turned on by it, but she was still trying to keep things hidden. I was able to watch several times by sitting quietly (ok, jacking quietly) in my darkened living room as they fucked on our somewhat illuminated porch. At 19 he was already a natural bull and I found it very erotic to watch a young guy black guy ordering her around and treating her like a proper white slut. He always came on her face, which I appreciated.
A few months into it the other girl deployed for a year and my wife came up with a line about agreeing with her friend to come over and cook dinner for her boyfriend once in a while, and making sure the apt was maintained. This immediately turned into her going over there every other night for a couple hours and pretty much openly fucking him, although she still denied it. We were on the ground floor of classic cookie-cutter apts though, so all I had to do, most of the time when the blinds weren't totally closed, was stick my head around the wall between our porches to enjoy a view of her throating his cock or bent over taking it from behind.
The other hot one I can think of was her first job out of the army. She was the manager of a title loan place where she only had one employee, a 21 year old black guy that worked as her office assistant. I actually didn't know about this one at the time, and, even though I knew by then she was a bbc slut, and I knew she was spending hours alone with a black guy every day, at that time I thought she was only fucking the guys I found on AFF, and I still thought she had the good judgement not to fuck her own employees, especially ones 15 years younger than her. I was wrong on both counts. Several years later when she finally opened up about her slutty secret life I learned that she had a very active sexual relationship with him and they played almost daily. She even told me that she was in the middle of sucking or fucking him many times when I'd call over the year or so it was going on, which, of course, is a great turn-on.