Using non-brand oil for cleaning brake pistons I am having some problems with rubbing disc brakes and came to the conclusion that it might be because of &quot;sticky pistons&quot;. I would like to clean and lubricate them, as here.
This video instructs to use the same brand oil for cleaning them as is used in the hydraulic system. These brakes use mineral oil. Questions: 1. Is it safe to use another brand's mineral oil for this task? 2. Is it safe to use different mineral oil, e.g. watchmaker's oil?
This question is only about cleaning and lubricating the pistons, not about adding more oil to the system. I am aware that using DOT fluid is not safe—the question is about using other kinds of mineral oil.
Probably yes.
I am expecting them to have very different viscosity and boiling point, so I would rather not.

The idea is to have an homogeneous oil if some droplets are left over after the cleaning process (same oil in same oil).
However, it should be no problem if you use a different mineral oil. At worst, the different oil will hamper your braking effectiveness, at which point you will need to flush out all the oil from the brake circuit.