More transmission oil esoterica (total BS, perhaps):
The only concern regarding the composition of Hydra-Matic oil/lubricant used up to (through?) WWII was with oil produced by a "modern" solvent-refining method, as apposed to the oil produced by the "older" acid-refining method. Under certain operating conditions, the solvent refining process oil would gum/gel up. GM determine that a solvent-refined oil formulation that included sperm oil (whale oil) provided the required quality/characteristics. The GM code for that oil was WA-161.
There was a post WWII Type A automatic transmission fluid/oil but I do not know when it was specified
It looks like the Type-A, Suffix A automatic transmission lubricant came into use around 1956.
Type B automatic transmission fluid (DEXRON) contained whale oil; but,
DEXRON II, Type C fluid were developed/introduced (in the 70s - 1972?) because whale oil "production" was banned.
With regards to the topic of early Hydra-Matic oil:
Up through WWII (up to early/mid 50s), as long as the H-M oil was made by the acid-refining process, the main consideration, as posted above, was to use a grade of oil that matched the operating temperature (lighter oil in colder operation, heavier oil in warmer operation).
With regards to the post that tank/vehicle transmission oil was run though carburetors during WWII, perhaps this was an attempt at "upper-end or top-cylinder or top-end lubrication" (to keep valves from sticking?)? Different "snake oil" concoctions/devices were also used for this purpose, even before lead was removed from gasoline.
