Chosen Solution
I have 2 memory slots each with a 4 GB module. Can I upgrade?
The non-retina models can be upgraded up to 16 GB! You can replace one module or both as an example replacing one you could get to 12 GB (one 4 GB & one 8GB module) or swap out both to get to 16 GB. But before you make this jump make sure its going to improve performance. Often upgrading the HD to a SSHD or SSD will get you more performance bang for most. Here’s the Apple T/N which goes over the details: MacBook Pro: How to remove or install memory
