Mickl replied:

2 litres of oil in the drive way makes for a pretty obvious oil leak. If you have chased up all your obvious leaks and are still using oil then it's possible that your turbo needs an overhaul(assuming your engine is in sound condition) Check the intake system post turbo for oil as this is a sure sign. 2lt over 5000km isn't going to produce huge plumes of smoke.

Martyn (WA) replied:

Rich00,
If it's not falling on the floor it's going out of the pipe, can't go anywhere else. Do you have any evidence of oil on the back doors? Mudflaps places like that, as mentioned the turbo might be a place to start. Depending on what the reciepts are for you would be surprised at what $7000 will buy you for a diesel, not a whole heap. If the engine wasn't loaded initially from the word go you could find that the bores are already glazed, not being nasty but how qualified was the guy who built the engine, you can spend all the money in the world but if it's not machined and assembled correctly you may as well throw the money on the barby. Why did he sell the fourby after such a short time after the rebuild?
I spent about $6500 and did all the work myself, subcontracted the machining out and the replacement of the liners etc but did the rest. After the rebuild I towed my camper trailer up some steep (ish) inclines to work the sucker in. When I sold my GQ last week after 20,000 klms on the new engine it wasn't using a drop unless really pushed.
Check the breather in the rocker cover this sometimes gets forgotten when doing an overhaul, you may be pressurising the oil out. Take the oil filler cap off with the engine running and see how much crankcase pressure you have, compression test is good, make sure you have a high pressure test gauge for this not one from a petrol engine, if it lets go you'll know about it. Keep the shiny side up