[gs986]

i own a 1999 boxster tiptronic and ive been having gearbox problems lately so i just changed the entire gearbox and everything is going perfectly except when shifting from 2nd to 3rd after the 3rd gear engages and i rev it there is a period of 1 second before it is engaged again and works normally so my mechanic says that it needs to be driven carefully for a week or so so that the valves get cleaned and the oil takes its place is this true? or do i need to exchange the gearbox once again? thank you in advance for your help