does anyone know a good oil for an older Compur shutter; is there a new product among the synthetics which would make for more accurate speeds and which would n ot gum-up over time? The shutter I'm working on is a Compur with dial on top: sp eeds 1 sec to 200; spring cock on right side facing the camera and firing mech. on the left. It came with a 150mm Carl Zeiss Jena Tessar 4.5. If any one has exp erience this lens or shutter and could give me any info about characteristics of the lens and/or any info such as to date of manufactor, circle it throws, how g ood the optics are rated...anything. thanks in advance.