General X15 information

[Redheadedstepchild]

Hey so long short this is my 2nd X15. The first was an efficiency series and I was T-boned in northern Canada (ice road territory). Some time later I now have another Kenworth with an X15 this one is the productivity series. 450hp1650trq. I don’t know dick diddly iddly about the Cummins outside the manual and what I’ve been told by other people. So I’m hoping I can get some rumours or otherwise questionable information handled.

If it matters I run reefer, coast to coast always gross. I prefer trotting along at 68mph but if I’m light and the wind isn’t kicking my arse I’ll do 72mph.
I run fuel additive (currently a catalyst) but I won’t name them. It’s not for fuel mileage, but to just keep this bullsh*t bio diesel from clogging my filter, keep things lubricated, and clean, and I must say. It helps.
I run Oil additive to keep wear down. NOT LUCAS. I currently try different things which I won’t name again. I don’t expect a miracle in a bottle but if it can reduce wear a bit and make my baby run a bit smoother without causing harm. Why not?
Nothing added to tranny or diffs yet.
I like to try and do oil every 30-40k to keep warranty.

Truck currently has 55,xxx miles.

Okay. Now for the general questions.

I hear rumours that fuel filters should be done fairly frequently. I’ve heard as much as every 15,000miles. Is this true?

Is there any failure points I should pay attention to?

Is there anything in general I should maintenance more frequently for longevity?

Also any parts I should carry just in case. I already have the filters which I get for $60 when the dealer or Cummins sells them for $120 when they have them. (2021 x15 has brand new filter style)

In general any helpful knowledge would be amazing. But I am mostly concerned with FF at the moment.


** If anyone wants to know about any additive I use AND IM NOT ADVERTISING FOR ANYONE. I’d be more than happy to share privately or publicly whichever is allowed. But again I don’t use additives for MPG. I use them to keep things running clean, cause if this thing start having DPF issues I’m more liable to just set it on fire, then pay dealer downtime, and anything I share is simply my experience with the product.

Truck is brand new. So I will default to dealer for most things simply to keep warranty, anything I can get done by a 3rd party I will happily do so.

Thanks again everyone, and in the event my dumbass posted this and it’s a repeat please let me know. I’m using my phone and this forum comes up teeeny tiny and very hard to read effectively.

[tree98]

Welcome aboard!! Hopefully your a little thick skinned or you might not be here long.

Most of us here run a gallon of 80/90 gear oil at every oil change, it's been proven to greatly reduce wear internally. Gear oil still has additives in it that they had to take out of motor oil for emissions reasons.
Your stretching your oil changes out to far for a cummins. You'll end up carbon packed with a worn out cam at 400k the way your doing it. Here's the chart Rawze put together

If your average fuel mileage every 10,000 miles is ...

less than 5 MG -- Change your oil every 8,000 miles or so.

5 - 6 MPG -- Change your oil every 10,000 - 12,000 miles or so.

6 - 7 MPG -- Change your oil every 12,000 - 15,000 miles or so.

7 - 8 MPG -- Change your oil every 15,000 - 18,000 miles or so.

8 - 9 MPG -- Change your oil every 18,000 - 22,000 miles or so.

above 9 MPG -- Change your oil every 22,000 - 28,000 miles or so.


The fuel filter on the X15 is a 4 micron and they plug up quick. I change mine based on hours since my truck has PTO time on it not just miles. I change it every 400 hours. In my experience if I wait much longer than that I get a check engine light for fuel restriction and that's HARD on the high pressure pump.
Speaking of the pump, you'll need to rebuild the pump every 400k miles because they are known to fail and take out the engine to the point that it can't even be rebuilt, yeah it really is that bad. I know you only have 55k on yours so you got lots of time but just don't forget about it.

Next is an EGR tuneup every year to keep that system working properly because once it goes south it can be hard to get things straightened out again. Rawze made a video series about it. The engine in the video is an 871 ISX not an X15 but the information all still applies. Sensors are hard to get right now with the current supply chain problems so order them now and if your lucky you'll get them in 8 months or a year.

https://youtu.be/FhJxpyS5MpY

You own a cummins so you'll need to buy insite and an inline adapter so your not at the mercy of the stealership for every check engine light because trust me, your gonna get them. Hopefully your the kinda person that isn't afraid to get dirty and willing to learn how to turn wrenches on your own equipment because that's what we're all about here.

I almost forgot.... DON'T LUG IT DOWN BELOW 1500 RPM. This is extremely important if you want that engine to last. Otherwise you'll sink a liner in short order, it happens all the time. Hopefully your rear ends aren't geared to tall like a lot of them are anymore, making it hard to stay above 1500 and beating the snot out of the liners.

[Rawze]

(11-14-2021 )Redheadedstepchild Wrote:  ...
I like to try and do oil every 30-40k to keep warranty.

...

I don;t care what the manual says... 30k+ on oil changes is engine abuse!

Like the post above ... change it based on your fuel mileage!... according to the nuimber posted.. otherwise, it will be ruined in 400k miles or so and you will deeply regret it!.


As far as fuel additives goes... that is pipe dreams it its best. Keep drinkin' that kinda cool-aide and you'll find out the hard way over time that you making things worse and not better by dumping over-priced after-marketed crap into your fuel system!.

[Redheadedstepchild]

yeah my Cummins is geared to run 1400-1500 at 75mph so I normally run around at 1400 rpm doing 68.
Luckily I have a system that can pull codes so I’m set there and I have no fear of getting dirty. I used to work in the trades.

[Redheadedstepchild]

(11-14-2021 )Rawze Wrote:  As far as fuel additives goes... that is pipe dreams it its best. Keep drinkin' that kinda cool-aide and you'll find out the hard way over time that you making things worse and not better by dumping over-priced after-marketed crap into your fuel system!.

While I agree with you about most additives. Being a Canadian running up and down having at least an antigel at my disposal is good. I never expect fuel mileage from an additive. That’s ridiculous but if it can reduce smoke and lower regens. Cool. Can’t see that though.

[Lonestar10]

if your talking about those catylists that supposidly keep your dpf cleaner your dreaming and most likely reducing the lifespan of such systems due to the metal particles in the crap.

as far as algae i run bio all the time running in midwest i run 0 additive and have 0 algae...algae only forms when you run your tanks low at all times....every time i hit a fuel pump i fill to the top.

anti gel is a fine additive for winter. granted last winter i ran 0 additive as i have arctic fox heaters and a water heated davco. only gelled once while at home when the APU kicked out. in anything under 10 degrees as soon as my main engine shuts down my apu is on keeping the water warm which keeps fuel warm. anything under -5 i will high idle the truck if im in it over night.

[Redheadedstepchild]

(11-15-2021 )Lonestar10 Wrote:  if your talking about those catylists that supposidly keep your dpf cleaner your dreaming and most likely reducing the lifespan of such systems due to the metal particles in the crap.

as far as algae i run bio all the time running in midwest i run 0 additive and have 0 algae...algae only forms when you run your tanks low at all times....every time i hit a fuel pump i fill to the top.

anti gel is a fine additive for winter. granted last winter i ran 0 additive as i have arctic fox heaters and a water heated davco. only gelled once while at home when the APU kicked out. in anything under 10 degrees as soon as my main engine shuts down my apu is on keeping the water warm which keeps fuel warm. anything under -5 i will high idle the truck if im in it over night.

{part of post removed by Rawze. complete nonsense advertising garbage "feel-good" brainwashed statements!}

I’ve also been to places where the fuel started to gel really easy and where I’ve actually had tanks freeze, so if I can put something in to prevent that myself then for the additional five cents a gallon it’s costing me whatever. Because if you’re not really careful going from California to Ontario Canada and you can get massive temperature differences. And in Canada it gets cold enough that your fuel will freeze in the lines. But that’s not really why I posted here, I’m more or less looking for the pointers to run the commons because I hear different things. Like the oil changes, I’ll probably do my next oil change and do a sample to see what kind of condition the oils in and go from there. Because of the oil still good and clean at 25,000 miles then I’ll keep it at 30,000 mile intervals. But I’m definitely not doing the 60,000 mile intervals that Cummins is saying. That to me just seems crazy .

[Lonestar10]

Since your stock my opinions and things I would do.

Keep engine rpms 1400 or higher when pulling this will help with liner longevity. But can be a pain with stock ecm rpm controls.

Oil changes around 15k if mileage is good. This prevents premature cam wear.

Replace EGR differential pressure sensor and exhaust back pressure sensor every 200k-250k miles

Replace imap sensor about every 250k miles.

Run 1 gallon of gear oil I place of something like Lucas garbage. Gear oil has many additives good for the engine all Lucas does is make it thicker and dilutes additives.

From my experience at Crete carrier I wouldn't run these new low viscosity oils when truck I was in was put in the trial group my dd15 lost 15psi oil pressure at idle and 10psi cruising and I saw 0 fuel mileage gain. I personally use 15/40 rot t in my truck and all other diesels I own. Including Apu on my truck which I change every 3rd truck oil change screw the 2000 hrs carrier claims.. I would do this if I owned a refer that runs alot.

I keep the new davco filters from oil changes and don't install till old filter gets near replacement line on davco

Rebuild high pressure fuel pump around 300k miles

Since truck is new I would do a overhead adjustment now that it's had time for everything to wear in. Then once a year after that.

I run synthetic in all 3 boxes some here run good ole dino oils in them.

Run a strong mix of biocide every 6 months to a year. I run 20% bio fuel almost year round and truck is a 2016. So far tanks still look brand new inside when I look in with a flashlight before refueling

These are some things that I would do if I owned your truck and that I currently do to my truck. Granted that one box would become a no box if I owned it as the warranty ain't worth the paper it's written on unless you like sitting at home for weeks on end. But I'll also never goto Cali or Canada as they aren't worth the headache.

[Redheadedstepchild]

(11-16-2021 )Lonestar10 Wrote:  ... some things that I would do if I owned your truck and that I currently do to my truck. Granted that one box would become a no box if I owned it as the warranty ain't worth the paper it's written on unless you like sitting at home for weeks on end. But I'll also never goto Cali or Canada as they aren't worth the headache.

I think you, a lot of that what you just finished saying is really good advice and things to watch for. Although it is technically my truck I don’t have Call of lot of control over certain things. It is stock so yes I have all the ECM restrictions, I run 10W-30 mainly because I run in Canada and it gets cold. I’ll definitely look into the gear oil, I normally run an oil additive as well. Not lucas but a moly style