Bad Oil Filter: Signs, Effects, and functions

Engine oil is one of the most crucial components of a car engine. It lubricates the moving parts of the engine; helps transfer heat away from the system and makes sure the engine is in good working condition. Engine oil moves in the engine through a lubrication system present inside the engine.

As the oil circulates, it picks up impurities and this accumulates over time. These impurities can either be worn-out particles from the moving parts of the engine or gunk and debris that find their way into the system from outside.

To protect the engine and keep its internal components in good condition, these oil pollutants need to be kept away, and the component that helps do that is the oil filter. Learn more about engine oil here.

Engine Oil

This article will extensively explore the component “Oil Filter

What is an oil filter?

An oil filter is a mechanical device that sieves oil in an automobile thereby, preventing dirt, and unburned fuel from circulating through the engine system. It does not sieve engine oil alone.

Rather, it filters, transmission oil, lubricating oil, as well as hydraulic oil. The filter ensures that only fresh oil goes into the engine while it keeps off the dirt. It is used on cars, trucks, motorcycles, boats, airplanes, tractors, etc. Because of its extensive usage, the sieve needs to be treated or changed occasionally.

Engine Oil filter

Types of oil filter

Filters come in different types, shapes, and sizes. Some of them are explained below.

Full-Flow/Primary Oil Filter

A full-flow oil filter is also known as a primary oil filter. This is the filter commonly used in cars. While some filters are designed to sieve specific types of motor oil in an automobile, the full-flow oil filter is designed to remove impurities from any kind of oil used by a car’s engine system.

The full-flow filter is very efficient in low temperatures. Very cold weather can cause engine oil to thicken. In a case like this, if the filter isn’t flexible enough, sufficient oil needed to keep the engine running would not be adequately circulated and this can cause damages.

Full-flow filter is more flexible than other types of filters because it is designed to supply sufficient oil needed for effective performance regardless of the weather temperature.

Cartridge Oil Filter

Cartridge Oil Filter

The Cartridge filter is a type of full-flow filter commonly made of fiber, which sieves particles within the region of five microns and above. It is easy to use because it is mounted upright in an engine thereby, making inspection easier.

With a Cartridge Filter, an inspection can be done without draining your motor oil. Because it is mostly made of fiber than metal, it is easier to replace than other options.

Spin-On Oil Filter

Just like the cartridge filter, the spin-on filter is a type of full-flow filter. Its installation is simple and requires regular tools thereby making it easier for car users to replace it themselves. It has a paper element enclosed inside a steel canister.

The spin-on filter is made of several parts including the steel canister, drain-back valve, bypass valve, and gasket.  

Spin-on oil filter

Bypass/Secondary Oil Filter

A Bypass filter is designed to support the vehicle’s full-flow filter. They work independently of primary filters and are designed to clean less than 10% of the motor oil used by the engine.

This filter removes contaminants that may have sneaked past the full-flow filter thereby, providing additional protection for the engine and extending the durability of your motor oil as well.

Centrifugal/Spinner Oil Filter

The Centrifugal filter is a type of secondary filter also known as "Spinner Oil filter". It works by spinning the engine oil around in order to trap oil contaminants. Spinner filters are made up of two sections: a housing chamber and a membrane.

Centrifugal or Spinner Oil Filter

As it spins the contaminants are thrown onto the filter media. The force generated by some of these filters is about 2000 times the force of gravity, making them efficiently remove the tiniest contaminants from the motor oil in your automobile.

The base gasket of this filter is not very durable but it is one of the most important parts. It prevents oil from leaking, which is a very crucial function. It is, therefore, advised that you check your base gasket with an auto mechanic every 2 to 3 months if you have this type of filter to ensure it is in good condition.

Thermal Chamber Filters

The thermal chamber filter has two methods of filtration. First, they simply filter the motor oil to eliminate contaminants, then, they refine the oil by boiling it to heat off additional contaminants. This process works with electricity and this reduces fuel efficiency.

Magnetic Oil Filter

Magnetic Oil Filter

The magnetic filter provides secondary support to a full-flow filter just like the centrifugal oil filter. Magnetic filters, however, are designed specifically for the elimination of metallic contaminants. They do not remove dust and grime. Unlike other filters, the magnetic filter doesn’t need to be replaced. Simple cleaning should do the trick to keep this filter functional.

internal view of a magnetic oil filter

What is the Function of the Oil Filter?

The basic function of any filter is to clean the substance passing through it, thereby, allowing only the desired substance to come out of the other end in its purest form. This is the same function performed by the filter. It purifies oil by trapping particles mixed up in the oil.

This process ensures that the quality of the oil coming out of the filter is better than the one initially absorbed. By cleansing these impurities, the filter massively reduces the wear of an engine hence, extending the life of the engine considerably. With this, efficiency is guaranteed.

The filter also removes worn particles, absorbs pollutants, and suspends the soot that results from fuel combustion. This allows the engine oil to perform numerous functions like lubricating the moving parts, keeping the engine cool, and sealing the piston ring. Contaminants can be organic or inorganic.

They include glycol, water, oxidized fuel, dirt such as dust, wear particles from engine parts, as well as wrong oil. For the oil to perform its functions efficiently, it should be free of impurities. Watch this to see how an oil filter works.

What Happens When You Install the wrong oil filter?

As earlier, mentioned, the filter is important in maintaining oil pressure, so when a wrong filter is installed it can negatively affect oil pressure. A wrong filter, a poorly functioning oil filter, or a clogged-up sieve can cause oil pressure to drop. Installing the proper oil filter along with the pressure relief valve will, therefore regulate oil pressure effectively and eliminate spikes.

In a situation where the relief valve is damaged, or the wrong filter is installed, too much or too little oil will flow into the engine and this can’t be good. Learn more about oil pressure here. Installing the wrong filter could prevent the filter from sealing properly.

This, in turn, could create problems of low and high oil pressure or leaks. Having an oil leak would make a mess on road or on the floor of your garage, and if your engine eventually runs out of oil, the damage can be catastrophic.

The engine will dry out and without oil to help dissipate the heat generated, your vehicle will overheat. In the absence of oil for lubrication, friction increases, causing engine parts to wear out and straining the cooling system. Unfiltered particles can also find their way into the internal parts of the engine and such particle deposits can obstruct heat conductivity.

Signs of a bad car oil filter

Strange Sounds

A drop in the oil circulating the engine means less lubrication for the metal components of the engine, this will result in grinding and rubbing together of metal parts, and the product of this will be a lot of heat. This also will also cause a lot of strange metallic sounds to be heard too. The intensity of this metallic noise would be more intense as you attempt to accelerate your vehicle.

Overheated Engine

When an oil filter is clogged up it limits the flow of oil in the engine, and if it goes unattended and gets too bad, it won’t be able to find its way into the engine. When this happens and the moving components stop being lubricated and cooled down by the oil, it will generate a lot of friction and heat and this causes the engine to overheat.

There is a temperature gauge on the dashboard indicating the temperature of the engine, whenever the pointer starts moving towards the red zone it means the engine is no longer cooling down and is getting hotter, once it is at the red zone the engine is overheating and this can be bad.

 Car Overheating

Reduced Oil Pressure

On your dashboard, there is an oil pressure gauge to let you know if the pressure of the oil is normal or not. When a bad filter is preventing or reducing the flow of oil into the engine, the oil pressure will be reduced.

This drop in pressure will be reflected on the pressure gauge on the dashboard of your car immediately and you can see the pressure drop further as you accelerate the vehicle.

 Reduced Oil Pressure indicator

Low Engine Power

For an engine to run smoothly and efficiently clean oil is supposed to be running through it. Once the filter is bad and oil stops flowing properly, you start noticing a stuttering sound accompanied by jerking.

This shows that the engine is no longer running smoothly. As a result, the engine starts experiencing difficulties producing power when you step on the accelerator pedal. This will cause a reduction in both the performance and acceleration of the engine.

 Low Engine Power Indicator


Clogged filters can cause sputtering. Cracking sounds would be heard as you drive and will be more obvious during acceleration. To add to this, your car will start falling to attain its usual speed. Once you begin to experience this situation, check the filter and replace it if need be.

Dark Exhaust Fumes

Exhaust fumes are mainly transparent and in some cases they are white. Each time you accelerate and notice very dark exhaust fumes coming out of the exhaust pipe, it is an indication that the filter is probably bad and urgently needs a change.

Exhaust fumes should never be black or brown because it indicates that the fumes are dirty which could be the result of a clogged or damaged filter.

 Dark exhaust fumes

Effects of a Bad Oil filter

If the filter is left unattended and is completely clogged up, oil circulation would be disrupted and the moving parts of the engine would not be lubricated. This might cause the vehicle to seize up, causing complete and total loss of power eventually. When this happens, it can cause a lot of inconveniences.

Can I drive my car with a bad filter?

If the oil is leaking slightly, you can. However, you have to be careful not to run low on oil and it puts your car into a continuous oil-change regimen which is not a very wise financial decision.

An oil filter is priced at about $7, and it can be changed by an individual in about 5 minutes of dirty work, while engine failure will cost you thousands.

The comparison is a bad reward/risk ratio. Change your filter as the car manual suggests, even when it seems unnecessary. Better safe than sorry. On another hand, if the oil is leaking so much that you can smell it, that is bad. It could mean that the filter is old or has gone bad. In this case, it is advised you visit a repair shop for repair as soon as you can.

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