Again might not be the correct term to design this HG calibrator thing that sits on top of the air filter housing..anyway as is on my 1994.

First question does it actually register at wich HG the vacuum is inside the box or it indicates it while the engine is running only?

On my truck the yellow disc is right at the top out of even the smallest graduation onto the bowl and I wonder if this can be even with a new filter?In my mind there should be a small resistance whatsoever and the disk should be down within the graduations marks no? Visually the filter looks OK but I've read not to use visual inspection of the filter as this could be misleading.
I have some oil leaking from the compressing side of the holset and trying to source anyother possibility than leaking seals to explain this and the Holset manual mentions something about restricted air intake to the turbo as one of few possibilities..
thanks,
Ron.

 

Filter minder is the correct word. These devices are so simple that it's almost impossible for one not to work. It's not reading because your filter isn't plugged up or you don't have enough mods to draw more air than the filter can flow. Filters tend to start plugging up faster once they start plugging.
Trust the filter minder, these things have been used with great success on diesel engines for over fifty years.
Real good info on them here, especially the FAQ section http://www.filterminder.com/

 

Thanks infidel...you surely know where to find all kind of infos!