I use Mobil1 15W50 in the 300D (summer car) and 5W40 in the 240D (winter car). Both have given good results over dino.

My car didn't start yesterday It was around 5 F and I had to plug in the block heater for 45 minute before it'd fire up., then ran rough with lot's of foamy fuel in the IP return line. It took 8 miles of driving before the foamy fuel cleared up. Does that sound like gelled fuel? I know my starter is weak and the battery is 2 years old and I will get the battery checked (again).

I have a 5 gal plastic tank for my diesel tank in the trunk (main tank is for VO) and the neck of the plastic tank had a few white ice crystals on it. Is that normal frozen condensation in this cold weather or do I have too much water in the diesel? Do you ever see ice cystals on the neck of your tank. After the engine warmed up I switched over to VO and it ran fine. I'll be adding some anti gel to the diesel tank and see if it helps.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked