First of all thanks to all for the support.
Now an update:
- I tried to replicate the topping/bleeding mistery. Mistery ended: no
bleeding at all.
- On the other hand I was finally able to spot tiny drops coming from
the rad matrix (probably). Saw them in two places. The origin may be
the same.

I am leaving for a trip and will follow this after my return.
In the meantime: what are the typical brands of the "bar leaks"
products? Are they effective in an oily environment such as the
coolant? And can't they create problems with the overall efficiency of
the system ?
Thanks again,
Jorge


"RoBe!" > wrote in message >...
> "Jorge Fonyat" > wrote in message
> m...
> > A4 2.8 1996 - 46,000Km
> >
> > Coolant is slowly decreasing. About 1 month from max to min.
> > No leaks, smokes or smells.
> > Temperature - oil & coolant - Ok.
> >
> Had this on a 90 a few years ago , it was a microscopically small crack in
> the rad matrix , so I suggest a bottle of "bars leaks" in the rad as this
> will gum up minor holes for a while , should prove the theory , and costs
> less than £2.00