I replaced my front pads this weekend. At 50k, my pads has tons of meat left. Probably 30% left. Caliper slide pin grease was also perfect. I left the OEM rotors alone, they're probably good for 100k+.
I'm not even going to bother checking the rear pads.
After I replaced the pads, I looked into those slots. You could not see any pad material, just the rotors.
There is literally no way to see the pads from those peep holes. Whoever designed that should be fired.
The only way to check pads is to remove the open caliper.
