Amsoil 15W-40AME vs Series 3000 5W-30 in DD

[huntsonora]

I have a 2003 Dodge 3500 with the H.0. Cummins and was thinking about going to the 5w-30 oil that Amsoil has.

I do not have a bypass filter (yet) but it gets to be fairly cold where I live in northern CO. I daily drive my truck and use it when I am guiding hunts. I will go from CO to Mexico in January to guide down there as well. I tow a little but its not an extremely heavy load.

Any and all thoughts and opinions are appreciated. I had never thought of going to a 30 weight oil in my Cummins until recently and want to make an educated decision.

Thanks in advance

 

[skyship]

How many miles on the engine and does it burn much oil? Also what does Mr Cummins say the viscosity should be in winter??
How much you want to spend is also a factor as Amsoil is not cheap. If you are not pushing the OCI boundaries then a cheaper 10/40 might work better than a 15/40, although a 5/40 is slightly better for cold starts.

 

[huntsonora]

Engine has 185,000 miles on it. Its not even broken in yet

It does not use any oil between changes. I'm currently running 7,500 miles between changes and was using Valvoline PB 15w-40 exclusively until my last oil change when I went to Rotella 5w-40. I went to the Rotella to see it consumption would change but it didnt use a drop.

I dont have any leaks either

 

[A_Harman]

I think you're doing fine with RT6, but you should consider extending your OCI. At least double.

 

[ccdhowell]

I am running the Amsoil HDD 5w30 in my '07 Powerstroke right now. I know it's not the same engine, but the oil has held up well for me, and the engine seems to love it. It is quieter on this oil than any other I have tried. When I first switched I thought I might see a small increase in mileage, but it hasn't happened for me. I stick with it because it seems to run better on this oil.

Here's a link to my latest UOA. Link

 

[oggb]

Don't fix it if it ain't broke. 40-weight has worked well in those engines for a looooooong time.

 

[dnewton3]

The grade you choose would be beneficial depending upon exactly where you're at, but looking at the average temps (Craig, Ft. Collins, Sterling as "northern CO") you average lows are all from 7+ degF to 18+ degF. You probably don't "need" a thinner oil, but it's not going to hurt the engine at all, and could be an aide if you need that last little bit of cranking rpm when way out nowehere on a hunting trip.

As for the synthetic issue, that depends upon your OCI plan. Greatly extended OCIs are the bailiwick of syns. Short to moderate OCIs can be easily handled by conventional lubes.

So, if you combine your matrix, you could go anywhere from a thin conventional (HDEO 10w-30) to a thin syn (5w-30) to a thicker conventional or syn (15w-40).

Generally, the engine itself isn't really going to care much. So it depends upon your use and plan.

To really know what is "best" you're going to have to do some UOA testing over several applications and see for yourself.

If you want a really good compromise in a readily available product, consider the T5 in 10w-30 from Rotella. The cold crank rating is as good as their T6, it's cheap (around $13 right now at W/M) and it will really go the distance. Not that the Amsoil products cannot suffice; they certianly are good products. But if your OCI plan is "normal", you'll never get the ROI out of them.