[Latitude 28]

I have had cylinders in the most difficult environments that never leaked and have wondered the same thing. If you look at the end of my cylinder you can see the wiper seal deteriorated.  That seal has no pressure on it at all....pressure is retained by the "loaded U-seal" an inch or so inside the block.  The wiper seal came out in tiny chunks of rubber and in fact stained my rag black indicating a degrading rubber.  All the other HWH components i have rebuilt were in the same condition when they leaked.  It would take a chemist to analyze what is going on.  I do know this from distant past experience "brake fluid" and "mineral based" hydraulic fluids ARE NOT COMPATIBLE.  If someone put brake fluid in the HWH system thinking that was okay it would cause what we are seeing.