2000 cummins hard start and smoke on startup.
 

2000 dodge Ram 3500 4WD 1 ton duelly. Stock as far as I know. 236500 miles, daily driver, usually around 20 miles to work and back, a little more on weekends.
Just started, usually just flip the ignition key over motor cranks with just a little black smoke. Started yesterday, did not want to start, turned over several times, when it did start, had a miss, for a couple seconds, with white looking smoke. My first thought is leaking head gasket, or leaking something. Have not added water, or oil. Checked oil and it had a greenish tint to it. Oh, and its been colder than usual here for the last couple weeks, if that matters. I am new to diesel ownership, but many moons ago, about 30 years ago, was a mechanic. Things have changed and are a lot more complicated. Thanks for any input.