I slipped 8gb into a friend's Macbook 2010. It was an upgrade from 4gb. It lead to significant performance increases running El Capitan. I read that I could have put in 16gb (not officially supported above 8gb, but in practice it works), but I didn't think that would be much performance improvements from 8gb and the cost of those larger RAM was going to be a lot to put into such an old machine. Still quite a success. Probably helping friend get another year or maybe even three more out of that Macbook. If Apple offers upgrade to OS though, I've advised her not to upgrade from El Capitan. I think any more OS is going to swamp this machine, 8gb or no 8gb. Of course an SSD upgrade would be the real baller upgrade to do on her machine.