Okay, so I drained my angle drive and refilled with Royal Purple 75w/140 as recommended by our own rabtech , current milage is about 8600.
Magnetic drain plug (standard on 2019 SLR) had a layer of black sludge on it - probably metallic particles, so it was time to change. Old oil was grey translucent, not black.
Refilled with pump until each press of the plunger produced an essentially equal outflow, very easy, capped everything off. Was surprised that angle drive took only 1/2 of the quart bottle. Is this correct? Looked all over for angle drive capacity and couldn't find any figures.
Can't see how it could hold more, guess I'm just a wrench rookie looking for some confirmation that I haven't screwed anything up!