Where is the oil sender located on a BBC? Above the filter are two ports. The port in the center above the oil filter (where I have the gauge) is a 3/8 thread and the smaller one to the left is a 1/8 thread. The sender I have has a 1/8 thread. I presume this is where it is located but some (people on the internet) say to mount at the front of the engine near the oil pan. There is indeed a 1/8 port there but it's kind of an awkward location and I don't think I have ever seen an oil sender mounted at the front of an engine. However, it's unlikely I would have noticed where it was mounted.