What oil can I use in a 99 Durango
10W40 is really a Diesel oil in today's oil market, most likely it will work but I would stick with the 10w30.
Yes you can use it, I live in Iceland so it´s rather cold here and 10/40 is reccomendet here but also if you have a small oil leak it can help to get a thicker oil like the 10/40. You have different 10/40 for the Diesel engine and it´s labelled for petrol or Diesel.
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