Interesting! I was aware that dot 5 + is not compatible but most publications suggest 3 and 4 are - but don't use them on track.
I will check thanks. No sign of leaks however.
Um. Brake cylinders, like those found in the disk brakes on all four corners, have nifty little shiny pistons that push on the pads that make the brakes brake. Each of those pistons have bitty rubber o-rings, sometimes two per piston, that keep brake fluid in and not out. A leak anywhere around there would likely hit a spinning wheel and get deposited who-knows-where, and maybe only under high-pressure events. Or when the brakes are really hot. So feeling around back there and looking for excessive grime, yeah, you want to do that.
I’m just a lowly shade-tree mechanic, and not that good of one in any case. My advice is worth what you’ve been paying for it.
General rule of thumb has been that brakes are, in general, the
one item where a dealership’s repair department does a really good job. Mainly because after-failures with death and all, juries are filled with drivers who know perfectly well how brakes work, have no sense of humor whatsoever about a bad brake job, and the dealership is a large, brick and mortar operation with easily findable principals and deep pockets who a jury with the right mindset wouldn’t mind backrupting.
As a result, dealerships might put trainees on regular maintenance items like oil changes, but they tend to be more careful about the people who work on brakes.
The above isn’t 100%, of course, there’s always a bunch of idiots somewhere, but there you are.