For clean motor oil, you must have a working filter

If you have a clogged or bad oil filter, it can no longer perform its job, leaving your engine susceptible to failure.  PHOTOs/

What you need to know:

Your car’s engine needs one vital ingredient to help it run efficiently and smoothly; oil. However, the real unsung hero is the oil filter, which plays the vital role of keeping the motor oil clean and contaminant-free.

During minor service for your car, one of the many components you are usually advised to replace, especially after covering 5,000km, is the oil filter. As its name suggests, the purpose of the oil filter is to purify the lubrication used to prevent friction in some, if not all moving parts of your car, for instance engine oil.

Alvin Nkini, a mechanic at Dalas Auto Limited in Ggaba, Kampala, says one of the primary roles of engine oil is to lubricate parts of the engine as they move and rotate around ton metal, without the lubrication element, the metals would grind against each other. But even with the presence of oil, it is hard to eliminate friction 100 percent from the engine.

The small component of friction that takes place is such that as the metals grind against each other, they produce very small particles of metal that do not dissolve but instead remain in the oil. The more these particles accumulate, the more they turn oil into a grinding than a lubricating paste.

“To avoid further development of metal particles, oil moves in the engine in a way that after lubrication, it must go through the oil filter which removes all the waste and metal particles. Besides, the heat from the engine changes the features of the oil itself. These features include oil viscosity (the thickness and thinness of oil). All the things that were changed from what they were and become waste are normally held by the oil filter,” Nkini explains.

“What goes through the oil filter after filtration is not supposed to affect the engine for the period it is meant to serve. That is why car manufacturers recommend a service period (normally between 5,000km to 15,000km), depending on the nature of the oil a motorist uses. As the oil filter removes the unwanted elements that are not supposed to circulate in the engine, it gives the oil the estimated lifespan to achieve value for money,” he adds.


An oil filter is positioned outside but very close to the engine block. This is because it is a serviceable part that should be easily accessed and swapped the moment you cover the mileage at which you are required to do service. The manufacturer designed them in a position that all the channels of oil have to come back to where the oil filter is positioned so as to clean the oil before it continues with its purpose in the engine. After undergoing the filtration process, there are several places the oil goes, depending on how the engine was made.

Some oil goes to the turbo to lubricate it, some to the cylinder head to lubricate the crankshaft while some goes to the Variable Valve Timing Intelligence (VVTI) sensors, either to advance or maintain the timing. The VVTI is the timing of the ignition of the car, which as a driver, you cannot precisely time to the required level. The computer system of VVTI engines was designed in a way that it automatically adjusts some parts in the car that you cannot adjust with a spanner or screw driver to enable the car improve its performance and efficiency.

Types of oil filters

Peter Amadi, a mechanic, says oil filters have types and brands. The components or the parts that put together an oil filter are more or less the same. However, oil filter designs differ, depending on the vehicle manufacturer. For instance, some filters have a paper element without the outer metallic sheet.

In this case, it is just something small that is fitted in a plastic cylinder before it is fitted on a car. On the other hand, the most common oil filters have a metal casing with internal components that serve the purpose of filtration and are replaced after covering a prescribed mileage. What differs is the size, depending on the design of the car and engine.

Servicing of oil filters

Oil filters are not serviced but are instead replaced. They are replaced depending on the oil type you use.

“Oil and other lubricants are always given a timeframe, after which they must be replaced. When replacing the lubricant, it is recommended to replace the oil filter as well. This means that when replacing engine oil, you must replace the oil filter while sticking to the same engine oil type and oil filter brand as the one being replaced,” Amadi explains.


The cost of oil filters depends on the brand. Some manufacturers take time to use the best materials on the market to come up with good quality filters, while some manufacturers are more interested in profit and come up with substandard filters.

In Kampala’s spare parts market, Amadi and Nkini agree that differentiating genuine oil filters from fake ones is tricky. The best solution is to stick to a reputable workshop or dealership from where you can raise complaints or get spare parts warranty in case there are mechanical faults with your oil filter.


Not replacing the filter can lead to unfiltered oil circulating throughout the engine, ultimately causing irreparable damage to your car’s internal parts.

Once you have driven 3000 miles, the oil has passed through the filter approximately 12,000 times. This is usually considered the right time to get your oil filter changed. Many manufacturers recommend replacing your oil filter each time you have your oil changed.

However, it depends on the make and model of your car as well as the oil type. Consult your owner’s manual to determine how frequently you should change your oil filter.