Oil change interval confusion

[Rustymayes]

I have a 2022 Dutch Star 4081 with a Cummins L9 450 HP power plant. The owner's manual has a service interval chart that has different milage between oil changes depending on MPG. At 5 to 7 which is what I experience the book recommends up to 30,000 miles or 1500 hours or 18 months. I have always changed the oil on my cars and boats at 12 months regardless the mileage or hours. What do you guys typically do? I have not had to add any oil since I bought the rig back in October. I have under 6000 miles on it. The coach was built in February of 2022 but I have no idea when it was actually put into service by being driven to the west coast to the dealership. Thanks for the input.

 

[Rich W.]

On my 6.7 Cummins I use a 7500 mile interval. That will easily get me across the country and back so I can always do my oil changes at home. Cummins says 15,000 but the thing works hard and I consider just driving it normally to be “severe duty” so that’s what I do. It holds 18 quarts. If it had greater capacity I might push it to 10,000. If you want to get scientific about it use an oil analysis service - I’ve always thought that would be interesting but have never done it. I just figure more frequent oil changes are cheap insurance (around $120 and about a half hour of labor). If I had an ISL I’d probably push it to 10k.

Maybe next time I’m at 7500 I’ll try this: Free Test Kits | Blackstone Laboratories

 

[Rustycoach]

I used Blackstone for years at the shop for aircraft engines but it is best used to see trends over the life of the engine. I think you are spot on with doing early. I think I will stick with 18 months regardless of mileage. The book says do the fuel filters at 18 months in the fuel section. Then in the oil section it mentions to always do the oil filter when doing the fuel filter but then just lists mileage tables with no mention of 18 months. I think it was an oversight.
Do you use the Shell Rotella 10/40 4T oil?
We used it exclusively in the Cummins on my boat. I had two of them and each held 24 quarts. With two oil filters each, those services were quite spendy.

 

[MemoriesByTheMile]

I have considered the oil testing services as our Cummins engine holds 48 quarts. Add on the oil filter and the two fuel filters - just the oil and filters adds up to $$$.
Taking care of fuel filter changes myself. But still paying for oil service as I haven’t wanted to get setup for dealing with 12 gallons of waste oil on each change. So I tend to push towards the upper end of the oil change interval. But almost all the miles are highway so should be easier on the engine.

 

[CaptainGizmo]

Yeah, you've stumbled into this GREAT controversy! A sure "fight" will ensue...LOL

Funny thing, I just went through the thought process for our ISX, with only 7k in a year.

I can give you the BEST EXPERT'S INDUSTRY STANDARD, vs. "CUMMINS" aka "let's make money" approach.

The "experts" will take Oil Samples and enter that into their log-books; and trust me/them, that has paid off for warranty disputes! Does every coach owner do that, or want to? No...but we "should" if we truly wanted the "perfect answer".

So, these whole Manual references are kind of frustrating, in a way. And, sometimes, Cummins will actually CHANGE them along the years and not even tell us. Ask me how I found out...and they don't keep a history either.

So, bottom line is, DON'T WORRY AT ALL in terms of your engine; our measly usage won't put a bit of lubrication stress on them, no matter whether we change oil every year, 10k, or whatever. Even a huge and heavy 60,000 pound coach pulling a stacker is a cakewalk for a 605HP X15. I realize you have the 450, but still...it's not pulling heavy loads like a trucker, and most sources I've spoken with agree that you can easily push out to the longest period between oil changes.