My parents were both born in Ohio, but my dad’s family moved to SoCal when he was just six or seven, but he retained the Mid Western accent. He’s say “greeze” for “grease” and “warsh” for “wash.” I hated the way it sounded, so I remember using the more standard pronunciations when I was pretty young (maybe 7 or 8). My older sister especially would razz me about it and pronounce “wash” for instance with a super broad ‘a’ like "waaaash."However, everybody (except my dad) changed to “my” pronunciation over the years. The influence of TV maybe? I was a little kid in the 50s.