356 's & 912 's used three types of oil filters. The mann filter was used for the most part on early 356 (or pre a ) and possibly a few very early a 's. This filter is identified by a 10mm bolt. The rest of the cars used either the h-filter (which is identified by a 16mm bolt) or the fram filter (which is identified by a 12mm bolt). Since there are no chassis or engine number breaks which denote the use of these filters, it is best to measure the bolt to identify your filter. Also, h-filter canisters are generally either all silver or silver with a black cover while fram canisters are orange with a black cover.