It could have been the treadmills I was running in that caused shin splints too. I started running outside for years after I had that problem. I have a treadmill at home now and just run in that and have never had problems. It's more efficient to just get it done at home.
I am better about buying new running shoes too. I wear Mizunos, which seem to be better for my legs than the clod hoppers I was wearing when I first started running.