Give it a shot, although at 85 years old you may have to manage your expectations.
From snippets she mentioned when I was growing up, my paternal Grandma had a wealth of information about hers and my Grandpa's families. When I came to look in detail at my own family history, she was dead, which was frustrating. And when I discussed my findings with my uncles and aunt, I knew more about their uncles and aunts and grandparents than they did, even though they all largely lived within a few miles of each other in a Lincolnshire market town.