45W or 60W MagSafe Power Adapter

I have an old MacBook made in mid 2010, 13-inch, Processor 2.4 GHz Intel Core 2 Duo, with 8 GB Memory. Unfortunately, the power adapters don't hold up for longer than 3-4 years before the connections start to fail. It's time to buy another one and I realize that I have used both 45W and 60W adapters. I went to 'About This Mac' in my Menu bar and could not find information stating which wattage I should be using. It only told me that I'm currently using a 60W adapter and that it is not charging (which I already knew). Does anyone know what size wattage I should be using for this particular MacBook model?