A Franz Unit
Brother of the Benz, Lightman
As a fifth year grad student at The General Motorts Institute, Flint Michigan my thesis was on lubricating oils and The Franz Filtration unit using 500 count double fold toilet tissue as a filter element.
Without going into a great deal of detail, The Franz process was at that time so far superior to anyother filterring methods that a number of the inplant rolling machines were converted and the oil never changed just the filter element.
I understand the Amsoil process is similar in that the filter is a celluious material.
One problem I could invision is the return drain line. In the past you used a sharp punch and knocked a hole in the oil pan and threaded a fitting into the convex hole.
With the M/B you would have to drill and tap.
As for the metric fitting, it is available at any parts house.
The Amsoil system could all be eliminate the gross changing of the oil; just refresh with 1 or more quarts every how many miles between filter changing.
I hope this helps and is of some encouragement to go further.
Happy Trails Beep Beep from The Spiderman in Houston!!!