Sure SF engines were well maintained but that high gloss red didnt last long. The silver just got resprayed often
I agree, and I saw lots of them in revenue service. (And ran som≈e.)
The colored paint was Dupont Duco lacquer, which soon lost its gloss in the sun and wind, and the mild acid spray at the Barstow "scrub" (engine wash track at the diesel shop). The color stayed true, though, and the paint was not chalky, just not glossy, sort of a very low sheen. And the pilots were sprayed with aluminum enamel every time the engines came to the roundhouse at L.A. There were newspaper photographers on hand at Pasadena for the Chief and Super Chief every day, as many celebrities began and ended train trips there, so Santa Fe, always image conscious, made sure there would not be a mark on the front of the rednose diesel pulling the train.