There's no bolt in the middle of the top.just 4 bolts into the engine block. The canister is vertical. I can't post pics due to my slow DSL server.Someone converted to a top bolt, one single bolt in middle of housing and held to block with four bolts. Unless you have one of those later sideways mounted filters that angles upwards.
The cylinder and top both have BMW and Purolator in raised letters. Also, there are no marks on the cylinder from any kind of tool used to remove it,so it must spin off by hand.A copy of a pm sent to me by Drew. I am still scratching my head!!
"Bert, I got under the car and confirmed that my canister must be a spin-on type made by BMW. There is a smooth bottom and no bolt. I've seen the parts drawing and this canister is not like anything I've seen. I won't know what type of filter is in it until I drain the oil and try to remove it. Korman Autoworks had no idea what was on the engine they built for the PO back in 2005. The bottom has a BMW roundel and # 1266373."