I have just drained my R380 gearbox and was wondering where you would fill the system as it has the oil cooler fitted. As it requires 3.4 litres rather then the 2.9 on one without. Is it done through the normal filler on the side of the box? Also is there any trick to drain out the oil cooler system? The oil looked like it has not been changed for a very long time. Going to be refilling with the Difflock EVOLUTION 1 Fully Synthetic Gear Oil. :) Any thoughts would be greatful as this is the first time dealing with an oil cooled system, used to the LT77 boxes :). Ant