Ive found a few bits and pieces on 2nd gear issues for the same or similar models. What i have found is that since an oil change and when its cold, changing into 2nd gear (especially in the morning from a cold start) it is difficult and sometimes it crunches into gear (it doesnt grind...
W140, S500, 1996 (five speed): Driving in 'W' mode feels smoother and lighter than the 'S' mode for a reserved driver like me. The vehicle starts out in 2nd gear and shifts up earlier too.
Could it harm the gear or the engine in any way if always driven in W mode.