99-00 civic si. Does anyone know what the thread pitch is on the oil pressure sending unit? I heard its 1/8 british standard pipe thread (BST). Can I screw an 1/8 NPT into the block and be fairly safe it won't leak? If the sending unit is 1/8 BST can I screw it into a 1/8 NPT tee? It seems loose in the threads. I just want add an oil pressure gauge (while also keeping the stock sender) but also make sure its not going to leak. anyone?