.> VW holds the patents on these hoses and if it wants to it can prevent
any aftermarket manufacturer from making replacement hoses.

There are good reasons to replace your hoses, the above is not one of
them, or likely true.  I doubt that there are any patents on the hoses.
A hose with a geometry to fit an engine  is not unique enough to get a
patent.  There's nothing special about the VW hoses, except that they are
shaped for the engine.  2nd reason is even if the hoses were covered my a
patent, the patent would be expired now or expiring shortly.  In 1983,
the US, the US patent life was 17 years from issue.  In Europe it was
(and still is and is also for the US now) 21 years from application.
Because any patent in Europe has to be applied for before any exposure to
the public. it would have been applied for prior to 1983.  Note: Patent
are not renewable like trademarks.

I'm familar with the above because my company makes all its money from
patents and trademarks.

So change your hoses, but VW can't stop anyone form making them, no only
economic sense will stop any other company from making them.

John R. (holder of 3 patents)