Start up question for 83 240d
 

I have searched it, but did not find much with the diesel engines. It has been weird starting up this winter, I have lower viscosity oil 5w-40 in it, and the glow plugs are good I replaced 9 months ago and use diesel kleen anti gel. The starting up is not the big problem with me, because it will eventually start after enough tries. What my concern is that it makes a weird smell trying to start, but after the third or forth time it will start, but black smoke pours out and the same offal smell. What could the problem be? When it runs there is no smoke at all driving, it is just start up, so I don't think my rings are bad, but I could be wrong.