Or if the fuel mixture is ok then it could be that the oil you are using is simply too thin for the amount of miles that you have on the engine. An appropriate oil weight might be 15/50. That would stop the oil from seeping up past your piston rings and thus eliminating the white smoke. I use Mobile sythetic 15/50 in my 87.
1993 190E 2.3
2000 Toyota 4x4 Tundra