They were not giving you attitude just saying that their has been 1k pages of oil threads and you can find the best info by searching. Now as far as what weight to use no 30w oil belongs in a diesel Benz ever! Yes use only diesel specific oil. The best oil for a cold, cold winter is probably Mobil 1 Delvac( sold at walmart as truck and suv oil, with a yellow cap) 5w-40.

But DieselAddict nailed it.

If you want to extend drain times get a sample tested at 5k and go from their. I have no idea what kind of car you have but a 617 dumps a lot more soot into the oil then a 606 or a new CDI.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200