Paint Colors For Engines
According to SC literature the green is called Huntington Green (also written as Huntingdon Green). I haven't ever seen this colour on sale but it must be listed in old colour catalogues. It has less black in it than Brunswick green.
Many of the engines from the B series on (1945) were painted Indian Red (the same colour used by Queensland Rail for their old wooden carriages).
There were two shades of grey. They started using a pale grey in the 1950s and a darker Machinery grey in the 1960s. Also in the 60s they started painting some of the air cooled diesels a bright red. I've seen some blue engines from this period too, as well as some yellow ones. There were also some aqua coloured engines (blue-green). I can't give you exact dates when they began using these colours.
Many YBs were green with a black head. some YBs had a couple of yellow pin stripes on the face of the flywheel. Some of the first diesels (the Y types) were painted black and others were green. I've been told that the experimental engines were usually silver.
Author, SOUTHREN CROSS ENGINES