solarman 216 is your best bet for advice on this , but as far as i know once empty , you refill it using the dipstick tube ... quite fiddly unless you have a funnel and a bit of tube :thumb2
When I did mine I took off sump cleaned filter and put back on. Now the manual for the 03 model says that you need (I think) 8 litres however this is only if you take the box completely apart just draining down with sump off leaves approx 3 litres behind in other orifices. so you only put 5 litres back in.
To replace oil I used a pump up garden sprayer and removed the sprayer hadle and just poked the tube down the dip stick and pumped away until it had all gone in.
ALL QUANTITIES QUOTED ARE OFF THE TOP OF MY HEAD AND REFERENCE MUST BE MADE TO THE MANUAL. (Does that get me out the shit if im wrong?)