Well, with the cold season all up on us, it's time for the ol' MB Diesel to start complaining.

Anyway, it got down to about 29-30 F here Monday night. My 240 refused to start that morning at 30 F. What the heck. It's been starting ok at 40, and last winter I didn't worry unless it was under 20F. But that morning, I had nothing. Barely tried to catch at all, glowed for over a minute. Hit once or twice on a cylinder. Tried several times but the battery was weakening.

Charged the battery for an hour or so about noon (45-50F) and tried again. Fired up pretty easy, little hesitation and ALOT of grey/white smoke (probably flooded her in the morning?)

So, here's my questions.
Would summer fuel (no additives) have thickening problems at 30F? I wouldn't think so. But, my clear primary filter was pretty full of crud, so I thought any thickening might hurt it. So, I replaced it. Then, I went out for a drive, got it warmed up and redlined it a couple of times. Blew out a nice cloud of black smoke the first time I did that. I also ran a can of seafoam through it (diesel-purge style, cant get purge locally-also never done a purge). Seafoam didn't seem to do anything.

I also tightened the glowplug connectors and put some powerservice winter additive in the diesel tank, in case it was thickening in the cold.

Here is a list of other info that may help.
-still have (probably pretty old) series glow plugs.
-I drive lots of short trips around town. (carbon buildup+charging?)
-Haven't checked valves in over a year. (on the list-of-crap-to-do)
-Running 15w-40 dino. (rotella-T)
-fairly new big battery. (800-850CCA, don't remember. interstate, i think)

I probably just answered my own question more or less. Do all this stuff. But, it's been starting fine, and this is only like 10 degrees less. Also, how much can that carbon buildup hurt. Can it make cylinders lose appreciable compression? And, lastly, what would the experienced recommend for a car that burns a healthy bit of oil run in the winter? I hate to be burning up lots of that 'spensive synthetic, but a thinner oil will burn more!

Thanks all for the help. I would imagine others are starting the winter worry over their diesels too. Good luck out there!

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'79 240D 4 speed manual 105k miles