I came across this picture of an Alamosa-bound freight with 20 oil tank cars (2 in the front and 18 in the back) that would have helped in keeping the refinery running.
(photo by Ross Grenard in "Requiem for the narrow gauge"
I remember watching a GRAMPS worker filling tank cars at the loading rack in Chama. I seem to recall that each side of the loading rack held 4 tank cars, so that 8 cars could be loaded at one time. But 1963/1964 was a long time ago, and I could be wrong about the number of cars loaded at the same time. Anyway, I think that the loading was done in a few hours once all the hose fittings were connected up. The Jim McKee's post of Jimmy's April 29, 1937, info suggests that loading was started at 2:20 pm, and a train departed with 11 oil tank cars at 6:30 pm, just 4:10 hours later!