The total cost is about 8 GBP or 10 USDollars, that's nothing compared
to cleaning up your driveway. Those fittings are available at almost
all shops that deal in hydraulics or better car accessory shops.
Mount all the stuff together using an sealing compound (not really
needed) or teflon tape between them. Cut a short piece of tubing off,
plug it with a suitable bolt (I used an stainless for show purpose).
You should use clear tubing so you can see if there's oil passing through
the valve. Fix the tubing to the adaptor with clamps. I didn't have
some at hand so I used cable ties as short time solution. Finally remove
the plastic turning knob so it can't be opened by branches on the trail.
Now if you have to change your oil you only take off the short plastic
tube and replace it with the rest of the plastic tubing. put the end
in a suitable container, open the valve with a small open ended wrench
and - voilà- drop free oil change even on a boiling hot engine.
This setup worked on my Defender 90 for several years even in the worst
conditions without ever failing. And I've no protection under that engine.
So don't worry.
The 200 TDi's have the 1/2 inch tread but 300's are different and
I can't remember the V8. But parts are similar, just the tread changes.
For those of you complaining about the small inner diametre of the
valve: It's 8mm, about 3/8". And if there are pieces larger
than that in your engine oil you are most likely to need more than
an oil change anyway.