Top 4 Engine Oil Sludge Symptoms

As oil flows into the engine, it carries some little contaminants – although most of these contaminants are trapped in the oil filter, some fine particulate ones escape into the engine with the oil and, over time, create sludge inside the engine.

Also, sludge can form when oil breaks down inside the engine and the additives separate. Oil sludge can reduce an engine’s performance; hence, it’s advisable to always check for sludge in the engine.

Engine oil sludge symptoms simply refer to the signs you’d most likely notice when there’s sludge inside your car’s engine. When you notice these signs, the best action to take is to drain the oil and clean out the sludge; this will significantly improve the performance of your car’s engine.

What Is Engine Oil Sludge?

This refers to dirt buildup inside the engine, which prevents the engine from running optimally as supposed. Oil sludge forms gradually as tiny particles flow into the engine along with the motor oil or if you typically do not change the engine’s oil regularly.

When there’s a sludge buildup inside the engine, the oil won’t properly lubricate the area where the sludge was formed, and that could cause other engine problems – fatal ones. If you notice any of these signs explained below, it’s time you check your car’s engine for sludge.

What Causes Engine Oil Sludge To Form?

1. Oxidation

After a while, the chemical ingredients used in formulating motor oils start to break down (oxidize); when this happens, the chemicals gather at the corner and form a sludge.

Oil oxidation can also occur when the engine’s operating temperature gets too high, and the oil is heated more than it can withstand. Hence, changing your engine’s oil at close intervals is recommended.

2. Bad Oil Filter

Another possible thing that could cause sludge buildup in the engine is a bad or dirty oil filter.

As the oil flows into the engine, it carries anything along its way; these particles carried by the oil are meant to be trapped in the oil filter, but if the filter is not in good condition, the particles will flow into the engine with the oil, and over time, cause sludge buildup.

3. Using the Wrong Engine Oil

Using blended or conventional oils increases the possibility of having sludge buildup inside the engine. This is because conventional and blended oils break down more easily than full synthetic oils, and when they do, the disintegrated ingredients gather at a place and form sludge.

4. Failed Crankcase Ventilation System

The crankcase ventilation system helps remove harmful vapors from the engine and prevents waste gases from getting into the engine.

If this system fails, oil could get into the combustion chamber, get burned, and form sludge. Also, the burned oil could get into the engine as deposits (vapor).

Engine Oil Sludge Symptoms

1. Oil Pressure Light Illuminates

The sludge in the engine would restrict oil flow into certain regions, which would send a signal to the ECU and trigger the oil pressure icon on your car’s dashboard to illuminate.

Notwithstanding, there could be pretty other reasons for the oil pressure light to illuminate.

2. Check Engine Light Stays On

Similar to the oil pressure light, the check engine light illuminates when the ECU detects there could be something wrong with the engine.

Also, not all vehicles have a dedicated oil pressure icon; hence, it is the check engine light that calls for attention to be given to the engine.

3. Engine Overheating

There are many things that can cause engine overheating, and oil sludge is one of them. The thing is, no one can predict where the sludge would form; it could form around an opening and block oil passage into that region.

When oil cannot saturate the engine properly, friction increases, which can cause overheating.

4. Grinding Noise While Driving

Sludges prevent oil saturation inside the engine, thus causing friction to increase within the internal engine rotors.

Due to lack of sufficient lubrication, the engine rotors would grind against each other and produce quite a loud noise you can audibly hear while driving.

Can You Remove Engine Oil Sludge?

Don’t use water to attempt to wash out the sludge inside your car’s engine; such an act would wreck the engine. For sure, you can remove the sludge by draining out the existing oil in the engine and refiling a new one.

Also, you could purchase and use engine sludge cleaners or, if you can, clean the engine manually and remove everything inside – you could have a mechanic do this for you.


These four (4) engine oil sludge symptoms are the commonest ones experienced by most people. You can prevent sludge buildup inside your car’s engine by using the recommended oil for the engine and going for an oil change at the right time.

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