Hello again. That big(over one inch) regular slotted screw at the oil pump
has a piston and spring inside.I have heard that people will replace the
spring , or stretch the current spring to increase oil pressure. I would
remove this and check to see the varnish and dirt situation inside the
moter.I think this spring/piston is the high pressure relief valve
assembely on the inside of the block.Maybe you can get the  dash light to
turn off by messing with this spring.California import parts has a special
spring for this in their catalogue.Dont know if  it is on their web
site.The vanagon has a regular beetle oil  pump, and I would expect this
spring to fit.If you got lots of varnish, maybe a bottle or two of "valve
medic"( Gunk- at flaps) will open things up enough to get more pressure to
the weak points inside this old wbx. Roger