Hello from Belgium!
When the Bombardier Iltis was introduced in the belgian army, there was already no more fuel with lead available. And the VW has the same motor. So no need to add lead (even if some iltis parts dealers sell lead additives - but they would also sell their grandmother... 😁).
I think Germany is the only country left in Europe, where you can still get 95 octan fuel with 5% Ethanol.
Since the 95 octan fuel became 10% Ethanol in the BeNeLux states, i switched to 98 octan. The old Rubber parts in the carburator don't like 10% Ethanol.
If you still have the old fuel-tubings, please replace them with new ones, that can withstand the Ethanol.
I replaced mine just before the introduction of ethanol-mixed-fuel with some old stock non-ethanol-proof ones. Even with the 5% Ethanol fuel, they started leaking and became brittle after 5 years.
Greetings
Peter