Oil leak from head gasket / oil filtration

[David Boyd <john@dboyd.demon.co.uk>]

Can anyone please offer an opinion re my '91 Audi 100 1994cc engine
code RT, which has started to weep oil from the head gasket just
above nos. 4 and 5 cylinders on the radiator side of the block. It is
more a slight seepage than a leak, and is probably the result of
starting to use thin synthetic oil  - the cam cover gasket is also
leaking a little. Should I just leave well alone or is the head
gasket likely to fail unexpectedly. The Archives had a fairly
inconclusive  discussion about re-torqueing (that's a queer word to
spell, hope it's correct) the head in such circumstances. Any
opinions would be * very* much appreciated, as am not relishing a
potential head removal exercise.

BTW, I noticed a firm here in the UK is marketing a device which
seeks to keep metallic particles suspended in the oil in the filter,
by means of a fabric belt rather like a bandolier containing powerful
magnets, which straps around the filter cartridge. The publicity
'blurb' states that filters can only trap metallic particles down to
so many microns, but the magnets can hold the smaller ones which get
through. A test of this, they say, is to fill a jamjar with used oil
and then attach one of the magnets to the lid, shake it about and see
all the metallic gunk attach itself to the lid............seems very
plausible and a good invention, but one wonders why it's not been
done before, if it's so effective - any views from those immersed in
(or should it be lubricated by) oil technology ?

Regards

David Boyd
Cumbria, UK