Need a little advise.

**tgreene** · 03-27-2011, 10:17 AM

I need a little help guys. I am running the premium cj-4 5W-40 but after watching the some of the oil analysis's I just didn't feel it was holding up as well as I thought. So I have been toying with the idea of switching to 15W-40 either the CJ-4 or the HD Diesel and Marine. I am going to put on a bypass filter unit when I go through all my fluids again this spring. I am also putting a new tune on my truck to get myself up close to the 550rwhp.

Let me know what you guys think, I am leaning towards the 15W-40 HD. Thanks in advanced.

**mrmanners** · 03-27-2011, 11:43 AM

Your original intent with going with 5W-40 was the lower cold pour point right?

**tgreene** · 03-27-2011, 12:14 PM

Yes that was my original intent but I might have been thinking like a gas engine and not like a diesel engine. Diesels have been running 15W-40 for longer then I have been alive, so yea.

**mrmanners** · 03-27-2011, 04:41 PM

Temps in MI get cold but not that cold. You will be fine with the 15w-40 D&M. Besides you are also getting more TBN with the D&M which helps control the acid in your motor.

Just my two cents.

**tgreene** · 03-27-2011, 05:29 PM

yea thats what I was thinking as well.

**BigDaddyDiesel** · 03-28-2011, 06:16 PM

I have tested both with using oil analysis and I definitely will only run the 15w40 D&M, while running the CJ-4 fluid I had more wear metal increases over a much shorter mileage interval than with the higher tbn 15w40. I will not recommend running the 5w40 cj-4 for anyone running a truck that doesn't have the DPF...

**Heath** · 03-30-2011, 08:13 AM

That's a bummer the data is showing that. Theoretically that shouldn't be happening. I've seen a lot of comments on how the CJ4's in general (all brands) aren't holding as well. All the "lab" tests show these are supposed to hold up better than the older oils, but it's not happening in the field.
Based on this, I don't recommend CJ4 unless they have the DPF. I'm an AME guy, but if you want our best oil, it would be the HDD. Many shy from 5/30, but it's like gold

**BigDaddyDiesel** · 03-30-2011, 09:46 AM

I have to say that I have yet to try the HDD 5w-30. IDK, maybe it is my fear of running a 30 weight oil in it, but I have also not seen any negative feedback from anywhere saying that it doesn't hold up. But Heath is right on, the CJ4 oils regardless of brand have been receiving similar lab results across the board from what I have seen and it makes me wonder too why the initial lab reports showed it holding up better than the older versions.

**Jers 6.6** · 04-08-2011, 03:19 PM

So the CJ-4 5W40 that I have already paid for is not the best for my 189K motor huh? Dang it... I went though difficult times to get it!

**mrmanners** · 04-08-2011, 08:37 PM

Actually it is. Because you live in AK, with temps getting super cold in the winter you want the 5W-40 for the lower cold pour point. When its at operating temperature, you have a 40 weight, just like the 15W-40 we use here in the south.

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