McCauley places red dye in the lubricant of the hub so, if a leak begins to occur, you'll have witness marks from the leaking lubricant which otherwise might be too thin as to be invisible.
And, as for the OP question, I haven't a clue. My library does not include a McCauley service manual.
Edit:
In the McCauley Propeller Owner & Operator Manual, you get this:
"(6) Internal Lubrication - On some models, grease is applied to the bearings for lubrication when
the propeller is assembled. However, on other models the lubrication medium is oil. On oil-filled
propellers, the hub cavity is partially filled with red dyed engine type oil which is sealed in the
hub and isolated from engine oil. This oil provides lubrication and corrosion protection to blade
bearings and other internal parts. The oil is dyed red to aid in the troubleshooting of suspected
propeller leaks.
NOTE: Periodic field maintenance of this lubrication is NOT normally required."
I also get this:
A-1637-11 Dyed Oil
(Piston
engines)
1 gallon of Aeroshell Oil W65 and 12
grams of A-4880-1
and
A-4880-1 Red "B" liquid
dye NOTE: A-4880-1 red "B" liquid
dye does not have a shelf
life