We want to re-paint a room. Walls are old plaster (presumably original,
so ~90 yo), with what looks like 3 layers of paint. Based on age, the
paint is likely oil-base. Some of the paint has pealed to bare plaster;
the rest seems well-bonded. So, primer has to bond to both plaster and
old paint.

Question: is there a preferrable primer to use? Or ones to avoid?

Thanks