Can I mix different CAS latency/frequency ram?

Hello everyone,

I have a 13-inch mid 2012 MBP. It has 4GB (2x2) ram PC3-12800S-11-11-B2.

I want to upgrade the ram to 6GB by keeping one of the current sticks and adding a 4 GB one. The best offer I found was of a Kingston PC3-10600 CL-9. Both CAS latency and frequency are different.

Will the system work based in the slowest status of the combined ram sticks (i.e., CL11 and 1333 MHz) or may I face compatibility issues? (or perhaps they don't work at all together)

Thank you very much!

Mario