No , it is only marketing trick to make us spend more money on the stuf we dont need. In fackt some studies show the gearbox runs much smother and quiter and last longer without any oil. Plus few kg of weight reduction
Not nearly as often as you do the engine oil, there's nothing inside the box to contaminate and clog up the oil but I guess it just degrades over many miles and heat cycles.
Maximum 50ooo km oil interval on maual thats being run as city comuter, Shorter if being run a lot on high way or street racing. Lets say at every second to third engine oil change. Your gearbox will apretiate it a loot. I dont whant to go i detail why. But oil degrades in first place. Espetially firs oil change should be earlyer then other as the gearbox beads in, and in that process small metal particles get in the oil which later behave as a grinding agent in the oil. But as most of the owners dont change the oil in the gearbox, and car company knows tat. They over engenier the gearboxses to last in very harsh working conditions
