I just bought a 1991 750iL, and while the German Mann or other brand oil filters probably are reliable, and with high capacity for dirt, they are still paper filters, and probably don't catch much particles less than 20 micron in size. The new fleece/synthetic filters appears to be excellent, and catching the soot particles that make the oil dirty, so the oil stays honey colored.
Are there any modern/synthetic oil filters with smaller pore size available for older BMWs?
Jan