I had a trans failsafe program which i dealt with by draining the oil, changing the filter and gasket. It wouldn't engage reverse or first gear. The oil was low and pretty black. I did a thorough cleaning and put the right ZF fluid in albeit pretty expensive. I got about 5.5 liters back into the transmission. Transmission now shifts nicely through all the gears including manual mode. The only issue I have is that the gear lever moves through the gears with difficulty. Is this related with the oil change or is it something mechanical? To go from park to reverse to neutral to drive requires great effort although the manual mode switching of gears is effortless. Any thoughts?