A few people have posted about how their crankcase hoses had been attacked
by the engine oil and had turned into "mush, jello, etc.". It seems to me
that one would design any rubber hoses intended for crankcase vapors/fumes
to be compatible with oil. There _are_ elastomers that are compatible (long
term continuous exposure type) with motor oil and the additives therein.
I have personally had engine coolant hoses that were attacked by oil that
leaked from a leaky cam cover gasket, but not crankcase breather hoses.
It seems to me that there are 2 possibilities:
1. that the rubber the hoses were made of was improperly specified by Audi
(design problem), or that the rubber was defective on manufacture.
2. that there is an oil or additive (unforseen by Audi) that is attacking
If people that have had rubber crankcase hoses / breather control system
rubber parts "go south" in normal use would tell me what oils you use or
were using when the parts got attacked, I'll compile the list and post it to
the list, and see if there are any common culprits.