Hey everyone, I am sure this question has popped up before; my apologies.

I have a 12 3500 SRW with 165k miles.

I am currently running 15W40 and am about to change my oil.

With February, I am considering trying 5W40 for a few months.

I live in northern Virginia, so it doesn’t get below 10F very often.

I just wanted to get some advice from all of you.

I have seen on other platforms that you get better MPG and cooler temperatures and stuff.

I thought I would ask the Cummins professional here because I trust the information you all provide to our community more than anywhere else.


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