The biggest thing I have seen that can kill Sub's is overheating from clogged radiators. I have known a few guys that have had to take there rides out back and shoot them because they didn't watch the warning signs. The second (speaking of experience with the EA82, not sure about newer engines)is if the wrong timing belt goes out first, you can throw a rod, although I have never heard of this happening. The primary belt is suppose to be made to go out first to disable the engine. I blew two myself in my younger, poorer days without injury to the engine.
I personally have an '85and1/2 Loyale out back that just needed new seals all around at 300,000+ miles. I didn't have the time to do the work and replaced it with a 98 Outback. It has sat for 3+ years, but has started right up each time I've messed with it.