I am going to do my first oil sample soon and I am wondering how is the best way to take the sample. I am not going to be changing my oil yet so I can't get the sample from the oilpan w/o making a mess. I am going to change my oil filter at this time so can I get my sample from the oil filter? which port in the filter is the "clean" side? the threaded hole or the ring of holes? It should work taking it from the clean side of the filter right(w/o contaminating the sample)?