Can I use PC3L RAM on my 2010 MBP?
I doubt that it will work. It depends on whether the 8GB 2Rx8 PC3L-12800S-11-13-F3 also works in 1.5 V mode (instead of 1.35 V - PC3L means PC3 Low voltage).

If 1.5 V are allowed you will find a similar question and answers here: Can I use DDR3 1600MHz RAM in a Mac instead of 1067MHz?

In the comments you will find the hint to keep one of the slower modules mounted  - then it may work if your MBP isn't too picky. I don't recommend the approach though.