how much transmission fluid on filter and flush
 

the owners manual say 16 .7 litres of sp Mercon oil

i drained the system and put in 13 litres and the dip stick says full when parked
engine turned off

That's about right for dry fill or flush. If you doing a drain and refill with new filter it will be way less. Start around 6-8 quarts and check the level. Check with engine running in park. Make sure to cycle through the ranges a couple of times before checking.