Pete A, based on your post count, welcome to the forums!
You mention using the correct type of diff oil in your post. Are you saying that most/some of the AU diff problems are actually just caused by using the wrong oil and if so maybe that they don't come with the correct oil from factory? Or were you just mentioning the oil as a side-note to the problem ie. not directly related to it? (I suppose this depends on the diff too now that I think about it - diffenent AU diffs used different types of oil and/or additives. This brings me to ask another question for everyone - which AU diffs were affected by these 'common problems' I hear about? eg. AU1/2/3, just 6cyl diff or 6cyl LSD or V8/XR live/LSD or
IRS w/LSD or just all or 'em were bad or what??
As a note, I haven't noticed any problems with mine yet (XR8 ute - LSD live axle). Car is only 27,000 odd kays though. I did dump the factory oil and fill it with fresh SHC ID when the car was pretty new though for what it's worth.
Steve.