Canadian mechanic suggests shorter OCI’s for 6.7 Cummins

[Redhawk454]

These engines sound like good candidates for bypass filters (if they're not already running them).

For what it's worth, when we lived in New Zealand for a year, there were a lot of diesel vehicles on the road there, mostly ex-JDM. The standard recommended OCIs were 5000 km for diesel and 10,000 km for petrol engines.

is a bypass filter just a secondary oil filter?

 

[Number_35]

is a bypass filter just a secondary oil filter?

All of the oil passes through a full-flow (FF) filter every time. Think of a FF filter as being in series with the lubricating system. Of necessity, a FF filter is limited to capturing particles about 25 microns or greater in size., or it would become blocked too quickly.

Only a small portion of the oil is shunted off to go through a bypass (BP) filter each time - think of the BP filter as being in parallel with the lubricating system. It can capture much smaller particles than a FF filter can.

Ideally an engine would be equipped with both FF and BP filters, but in practice a well-maintained engine with only a FF filter can outlast the rest of the vehicle.

 

[Fabulous50s]

I’m guessing (and I stress “guess”) is he’s referring to the EGR for running dirtier and perhaps DPF as to running warmer?

EGR, and closed crancase ventilation both contribute to higher soot formation in the oil. EGR adds a huge amount of heat to the cooling system, and raises intake temps.

Exhaust aftertreatment all adds up to higher back pressure which also leads to more soot in the oil, as well as higher oil temps.

See where this is going?

 

[NashNative]

His statement of

A 6.7 engine doesn’t filter any better, doesn’t hold any more oil, burns more fuel, plus it runs way hotter and dirtier internally, yet the manufacturer has increased the oil change interval recommendation.

has me wondering about the increase and increase and increase in oil change intervals by Cummins.

Did the oil rly improve that much? I’ve known for long that these newer diesels are dirtier internally yet the oil Change interval is 15k miles.

I found it by searching for 6.7 Cummins oil
Sludge buildup.

CK-4 & FA-4 oils, which were introduced alongside the 2017 EPA engine models, are up to 60% better at resisting oxidation than the previous CJ-4 category of oils. So yes, the oil chemistries out there today are significantly better than the previous ones. For some perspective, on Cummins heavy-duty engines...light duty cycle oil drain intervals between 2010-2016 were 25k miles...in 2017 that jumped up to 60k miles and then up to 75k in 2020.

Oil chemistry is improving...the filters are also, in some instances, improved to handle the longer intervals...and then the fuel systems combust much cleaner (as long as the fuel system gets the filtration protection it needs) so there is less 'soot' being produced to enter the lube system. When it's all working together, longer ODI's are totally realistic.

 

[totegoat]

Change the oil in my Cummins once a year if it needs it or not.

 

[GON]

Ford's 6.7 diesel recommends operator run 15w40. The exception is for severe service, Ford recommends 5w40. Instead of increasing oil change frequency, is Ford onto something by switching from 14w40 to 5w40 for "severe use", and if that is the case is 5w40 a better choice over 14w40 for diesel engines in light duty trucks?

 

[twX]

Ford's 6.7 diesel recommends operator run 15w40. The exception is for severe service, Ford recommends 5w40. Instead of increasing oil change frequency, is Ford onto something by switching from 14w40 to 5w40 for "severe use", and if that is the case is 5w40 a better choice over 14w40 for diesel engines in light duty trucks?

If their definition of severe service includes extreme cold weather, that's probably the reason for the 5W recommendation. A 15W-40 will retain a higher viscosity in high-temperature high-shear conditions and will provide better engine protection than a 5W-40 when oil temperature is high (hot weather, towing).

 

[GON]

If their definition of severe service includes extreme cold weather, that's probably the reason for the 5W recommendation. A 15W-40 will retain a higher viscosity in high-temperature high-shear conditions and will provide better engine protection than a 5W-40 when oil temperature is high (hot weather, towing).

Here is what Ford states:
A vehicle that meets any of the following criteria is categorized under the "severe duty" service category:


• Engine is idled more than 10 minutes within a 60 minute drive period, is operated at low speeds (under 25 mph) for extended periods of time, or is frequently operated stationary.


• Vehicle makes short trips with frequent stops and/or engine is frequently operated in a manner that prevents it from reaching full operating temperature.


• Vehicle is driven off-road or in dusty conditions.


• Vehicle is driven/operated in temperatures below -9° F or above 100° F.


• Vehicle performs light to medium towing exceeding 1,000 miles between normal oil change intervals.


• Vehicles performs heavy trailer towing.


• Vehicle hauls cargo at or near it's maximum payload capacity for extended periods of time.


• Engine is run on fuels other than ULSD, including all biodiesel blends.


Most Super Duty pickup trucks will fall under the severe duty service category; recommend 5W-40 full synthetic engine oil so long as vehicle is operated in ambient temperatures greater than -20° F.

 

[bismic1]

5W40 is a 40 weight just like 15W40. 15W40 offers no better protection in hot weather than does a quality 5W40.

Yes, due to the added VII for the higher viscosity range (5 to 40 vs 15 to 40), it will be somewhat more prone to shearing. In a quality oil over a 5k mile, or even 7.5k mile, OCI ........ this shearing is not an issue.

 

[loneryder]

Egr's do make them dirtier. If you had no egr, the oil would not get so black so quickly.

 

[OLEJOE]

ULSD made a big difference in OCI length. High sulfur fuel required more frequent changes to get the sulfuric acid out of the sump and the oils at that time were formulated differently than they are now.

 

[Redhawk454]

most of us are in the severe category.

 

[bullwinkle]

5W40 is a 40 weight just like 15W40. 15W40 offers no better protection in hot weather than does a quality 5W40.

Yes, due to the added VII for the higher viscosity range (5 to 40 vs 15 to 40), it will be somewhat more prone to shearing. In a quality oil over a 5k mile, or even 7.5k mile, OCI ........ this shearing is not an issue.

5W40 will be a full synthetic, while 15W40 is a blend, or possibly even conventional, so the 5W40 SHOULD be able to take extreme conditions better. As always, UOA is never a bad idea-for example, HEUI PSDs seemed to shear oils pretty fast.

 

[bismic1]

I agree, mostly. HEUI PSDs have no problems with 5000 mile OCI's! Some (like mine) do quite well at 7500 mile OCIs.

 

[b_b]

if i had a heui vehicle i would run archoil or some kind of oil additive. and go no longer than 5k. maybe even quicker if towing frequently.