Hi there, L plates you state the gearbox and filter need changing every 20k. I have a 54 2.8 limited and the user manual clearly states the filter and oil in the gearbox do not need changing under normal driving conditions, it only needs changing every 60k if the vehicle is used as a taxi or used for towing. However I can see your point as if you buy second hand you don't know if it has been used for towing or a taxi!