Cummins Diesel 6.7L Engine Oil Change Interval [Avoid Costly Repairs]

September 16, 2022 admin

Oil Change Intervals for Cummins Diesel 6.7L Engine

Although the Cummins Diesel 6.7L engine is excellent, oil change intervals need to be properly thought out. The fact that not all drivers are created equally must always be kept in mind. Do you only take brief vacations? Do you frequently go the distance? Are you considering switching to synthetic oil or sticking with regular 15W/40 oil right now? The owner's manual's recommended oil change interval should be adjusted based on usage.

When inspecting an "extended interval" engine, the valve cover frequently reveals a buildup of sludge. The pictures below demonstrate how hot and unclean a 6.7 engine with full emissions runs. If the owner had kept the engine in decent shape, he would not be today facing a $12,000.00 diesel engine repair expense. I think oil changes are fairly affordable maintenance.

We propose 6000 km (3700 miles) between oil changes if you are starting out with regular oil 15W/40. Driving in cities, driving in stop-and-go traffic, and idle time are all safe during this time. If you usually travel on the highway and take regular, long excursions where the engine may get nice and warm and run for a long period, certain vehicles can withstand a stretch of 8000 km (5000 miles) or more.

Driving beyond these distances puts your engine in considerable danger by allowing sludge and soot to amass. This knowledge is vital for the skeptic who reads this article and disregards the warning for an oil change that appears on the dash. The message is triggered by restriction across the filter and/or engine run length and does not genuinely monitor oil degradation. Older trucks powered by Cummins were advised to change their oil every 6000 kilometers (3700 miles). Despite the fact that a 6.7 engine doesn't filter any better, doesn't hold more oil, uses more fuel, and also runs hotter and dirtier inside, the manufacturer has extended the recommended oil change interval. As seen by the disastrous engine failures we've seen in our shop, we don't understand it. 

Why infrequent oil changes cause sludge and soot to build up

Diesel engines are inherently polluting. Due to the method that diesel fuel is injected and ignited, oil burners produce more soot than their gasoline-powered counterparts. The majority of that soot is expelled through the exhaust system, but a little amount manages to bypass the piston rings and enter the oil. For this reason, even after an oil change, diesel oil still seems dirty. As a result, it is suggested that high-quality, low-ash oil be used with the Cummins 6.7L engine. The soot might quickly overwhelm any additives in the engine oil, turning it into sludge.

Soot is increasingly common in diesel engines of recent generations, notably the 6.7L, due to sophisticated emissions systems. Devices that recycle pollutants into the combustion chamber include exhaust gas recirculation (EGR) valves. This increases the likelihood that soot will mix with the oil. Without such safeguards, soot buildup did not happen as quickly on older diesel engines.

The amount of soot may also increase due to outside circumstances. Rich air/fuel ratio and prolonged engine idling are two instances. At construction sites, diesel trucks are usually kept inactive. They are routinely modified using computer programmers and performance injectors as well. Due to their excessive improvement of the air/fuel ratio, both of these modifications have the potential to produce soot.

Oil Dilution

Another element that causes sludge formation in contemporary diesel engines is dilution. This is primarily the fault of the diesel particulate filter, which gathers soot escaping from the exhaust pipe. A "regeneration" procedure is required for this device to heat the exhaust sufficiently to burn off the soot. Fuel is introduced into the combustion chamber to cause this increase in exhaust temperature. Unfortunately, if the gasoline manages to get past the piston rings, the engine oil can get diluted and turn to sludge.

Sludge's effects on engines

Internal engine parts need to be lubricated continuously to reduce friction. Sludge is a subpar lubricant, and you don't need to be an expert in petroleum engineering to realize that. Sludge enables internal engine component friction to rise, which eventually causes overheating and component failure. It also obstructs the oil channels in the engine. Due to the oil becoming heavier in the winter because of the extremely low temperatures, this may become a major problem. The final outcome is a catastrophic engine failure with a high repair cost.

Longer drain intervals for the 6.7L Cummins engine

If your drain intervals are too long, you should think about upgrading to a synthetic oil. To ensure that your oil is in good condition, you must utilize an oil monitoring program. Oil analysis is necessary, but it can provide you with a reliable indication of the oil's quality. You can do this and travel up to 10,000 km (6200 miles), although more filtration is required, in accordance with our prior experience. Excellent choices include a bypass filter kit and a primary filter that must be replaced half-way during the interval.

How to prevent the buildup of muck

Frequent oil changes are a simple and effective way to prevent sludge development. Increasing the frequency of oil changes is a cheap way to protect your truck's engine.