The B-414,434,424 models were designed to use 90W gear lube in the transmission/differential. Some industrial models like 3444 used the transmission as a hydraulic reservoir with Hytran instead of 90W.
There is nothing wrong with using Hytran in the 424 transmission/differential but be prepared for some leaks. In fact Hytran is probably better for moisture conditions and operation in cold weather.
I can remember using our 434 in -25F weather and you had to leave the transmission in the gear you wanted to use the next day. It would take a good half hour of running before you could shift gears easily.