last winter i replaced the injectors on my 300sd , after a day or so i noticed there was fuel around the base of the injectors so i took them out and wrapped the threads with teflon tape and now no leak persists. Btw you can make your own socket if you wish by notching out the socket on opposite sides of each other if you want to save some cash.Its a bit of a time consumer but can easily be done with a grinder.