I believe the steering lube change is in the factory service bulletins of 1929 and perhaps 1930. Ford gave warnings about using grease as steering lube because it would not flow to all of the moving parts whereas the the liquid lube does.
As for the steering design itself, consider that the steering is / has:
> Poorly sealed, so a liquid lube will leak;
> Very high gear contact pressure, so the lube should be an excellent friction reducer with a superior squeeze-out performance;
> Poor lubrication of the sector shaft and its bushing when the original grease fitting was discontinued.
Considering we have access to modern lubricants that are far superior to the original stuff, for a driver / touring Model A, I would choose a synthetic steering lubricant, perhaps something the trucking industry has to offer.
I would also retain / add the grease fitting in the sector shaft housing that was deleted by the factory.
Last but not the least, replace the sector shaft friction bushing with a modern needle bearing & lip type seal. Parts suppliers sell the sector shaft housings modified this way.