Note: This information applies to all diesel engines. This includes popular Audi / VW TDI diesel, Mercedes BlueTec and CDI diesel, GM Duramax, Ram Cummins, Ford Powerstroke engines, and others.
Shortly after performing a diesel engine oil change, many people observe that their motor oil has already begun to turn black. Is this normal? In this article, we will briefly discuss several reasons why a diesel engine's oil turns black after an oil change.
In most cases, it is normal for diesel oil to turn black. This change is typically noticed several hundred miles after an oil change. This does not necessarily mean the oil is dirty or that the engine’s internals are dirty. Below are a few reasons why diesel oil turns black.
High Compression Diesel Engine Designs Cause Diesel Engine Oils to Turn Black
Most modern diesel engines use high compression to optimize torque and horsepower efficiencies and minimize emissions. While the diesel fuel is compressed during the engine's internal combustion process, more piston ring blow-by occurs. Remnants of the combusted diesel fuel turn to soot and when it moves past the piston rings it ends up in the engine's crankcase sump oil pan area, where the engine oil is stored. The soot created by a diesel engine combustion process is inherent to diesel engine design and is considered normal.
This diesel combustion blow-by is much more compared to a typical gasoline-fueled engine. Engines that combust gasoline do so at a much lower compression, creating less blow-by, and resulting in much less soot during the combustion process.
Diesel Engine Emission Systems Cause Oil to Turn Black
Most modern diesel engines also have higher soot concentration in the engine due to the diesel emission systems (i.e. EGR - Exhaust Gas Recirculation). The diesel exhaust gas recirculation system allows a select amount of exhaust to be re-ingested back into the intake system and combustion chamber. The increased combustion temperatures in the cylinders burn the fuel more efficiently, resulting in reduced exhaust emissions coming out of the tailpipe. The re-ingested exhaust gases also increase the contamination of the diesel engine oil causing it to turn black more quickly.
Why Choose RAVENOL Diesel Motor Oils
RAVENOL advanced modern diesel oils are formulated and include the specific ratios of detergents, dispersants, and antioxidants to combat and absorb ‘normal’ diesel soot while keeping the diesel engine clean and protected. RAVENOL diesel oils are also formulated and intended for extended oil change intervals in accordance with the vehicle manufacturer's recommendations. Anywhere from 10,000 to 60,000 miles depending on the RAVENOL diesel oil and application.
When should an engine oil cleaner or flushing treatment additive be used?
In most cases, oil additive cleaners are NOT required, especially in newer or low mileage engines. Engine cleaners should only be used after a physical inspection of the internal engine components has been confirmed.
How do you confirm if an engine oil cleaner and flushing treatment additive should be used? This can be done by removing the engine valve cover and inspecting the valve train area. If the valve train area is clean, it is likely the entire engine is clean and an engine oil flush or cleaning additive is not necessary. If the valve train has excessive oil deposits, black sludge, brown varnish, and oil breakdown, it is likely the entire engine is dirty and an engine oil flush and cleaning additive may be an option.
The engine oil additives market is huge in the United States. Many consumers are driven to purchase motor oil that is priced low. Most of these oils have a low price because they are made with low to medium quality base oils and additives. It might make sense to use a performance-enhancing engine oil additive with these types of oils.
When using RAVENOL USVO or CleanSynto oils it is a different story. RAVENOL products are not driven by price, rather they are driven by quality. RAVENOL only uses select high-quality base oils along with a sophisticated additive package that is engineered to meet or exceed your vehicle's recommended oil specification.
Therefore, our recommendation is DON’T use oil additives in conjunction with RAVENOL USVO or CleanSynto products. These exceptional high-quality formulations don’t need anything added to them. Adding an oil cleaner or additive to RAVENOL USVO or CleanSynto products will change or alter the oil formulation from its original designed intent and would adversely affect the oil's ability to provide maximum performance.