td5 auto oil change

hi. ive got a td5 auto .2001 my mechanic mate was going to change the auto gearbox oil.he hasnt done one before. he was abit concerned that looking at the sise of the sump that the filler /leval plug is in it doent look as if it will take anything like the 9.litres recommended.also as i am towing a horse trailor would dexron 3 be ok? many thanks.

Dexron 3 is ok, you can only drain some of the oil, half of that 9 litres max half remains in the torque converter.
Garages have a sucking machine that sucks the box dry of it's 9 litres.
If you drain again a few miles later then most of the oil will be fresh.

many thanks for the reply.