I bought my AU from the auctions as a repairable write off about 18 months ago, for the huge sum of $150! I have no idea of its history. It's a column shift 6 seater wagon, great for carting kids on the school run. As it sits, it only owes me a grand. We just use it as a second car, and since it's worth virtually nothing, we're not fussy where it's parked or what we cart around in it.
When purchased it had a huge oil leak from the timing chain tensioner, easily fixed with new o-rings. The oil I drained out was black, watery and stinky. It only had about 3 litres in it! I figured if the engine was buggered, I'd just throw another one in, but with an oil and filter change, and new spark plugs, it ran ok. I also did the inlet manifold gasket as the old one had split, causing a vacuum leak. There was a noisy lifter, which I tried to fix with Wynns Tune Up, to no avail. I ended up pulling the rocker cover off and found number 3 exhaust side lifter had broken, so I replaced it with another one I had laying around, then it ran quiet and smooth!
The poor old thing had been seriously neglected. I wish I had photos with the rocker cover off, it's one sludged up engine! I scraped as much as I could from the top end, then just left well enough alone. A series of 1000km OCI's with whatever I had in the shed didn't clean it up much. At the moment it has a mixture of Castrol Edge 5w30, GTX 15w40 and some Castrol Tection 15w40 diesel oil...and it runs great! No leaks, and doesn't burn a drop. These AU's are tough!
Sorry for rambling...