[Biturbos4] Any special way to lubricate s4 doors ?

[T Stifler]

Hello folks,

So my driver's door has gotten rather hard to open/close - slowly over time.
It's particularly obvious when someone else tries to close it and it half
closes.  I've attempted to lubricate it at all obvious points with a wd40
and then lithium spray.  No change - or minimal.  I remember Keman saying it
should be part of factory service - but then I took my car to the dealer for
the factory service, so that would explain why no attention there.  Any
special way to lube s4 doors ?

Thanks - TS