Oil filter with a replaceable filter element: purpose, design and principle of operation

The oil filter is one of those unnoticed but critical components of your car that directly affects the health of your engine. Many drivers know that it needs to be changed along with the oil, but not everyone understands how does it workwhy some models have replaceable filter element, and what are their advantages over non-separable analogues. Meanwhile, the right choice and timely replacement of the filter can extend the life of the engine by tens of thousands of kilometers.

In this article we will look at why an oil filter with a replaceable element is needed, how it is designed from the inside, on what principle it cleans the oil, and what nuances need to be taken into account when using it. We will pay special attention collapsible structures, which are increasingly found in modern cars - from budget Lada Vesta up to bonus BMW 5 Series. If you've ever wondered why some filters cost 2-3 times more than others, or why mechanics insist on original parts, you'll find the answers below.

Spoiler: Replaceable filter elements allow you to save up to 40% on consumables during each maintenance, but only if they are selected and installed correctly.

Purpose of the oil filter in the engine lubrication system

The main task of the oil filter is catch mechanical particles, which are formed in the engine during operation. These could be:

• 🔥 Wear products — metal shavings from rubbing parts (pistons, rings, liners).
• 🌡️ Sediments — carbon deposits, varnish deposits that form at high temperatures.
• 🛢️ Foreign inclusions — dust, sand, particles of sealants or sealants.
• 🧪 Oxides — products of oil decomposition during long-term operation.

If it were not for the filter, all these particles would circulate through the lubrication system, accelerating wear of parts. For example, metal shavings as small as 20-30 microns (the thickness of a human hair) can cause scoring on cylinder walls or damage to crankshaft bearings. According to research SAE International, a properly functioning filter reduces engine wear by 30-50%.

However, not all filters are equally effective. Cheap non-separable models often have low quality filter material and can allow up to 15% of contaminants to pass back into the system. While filters with replaceable element (for example, from Mann-Filter or Bosch) provide a degree of purification up to 98-99%.

Oil filter device with replaceable filter element

Unlike traditional non-separable filters (where the housing and the filter element are a single whole), models with a replaceable element consist of two parts:

1. Permanent Corps — a metal or plastic container with a thread for attaching to the engine. Inside the housing there are valves and fastenings for the filter element.
2. Replacement cartridge — the filter element itself, which is inserted into the housing and secured with a lid.

Let's look at the device in more detail using a popular filter as an example. Mann-Filter W 712/94 (installed on many models Volkswagen, Audi, Skoda):

Component	Material	Purpose
Housing	Aluminum or high strength steel	Protects the filter element from mechanical damage and ensures tightness
Filter material	Cellulose + synthetic fibers	Captures particles as small as 5 microns
Bypass valve	Rubber or silicone	Opens when the filter is clogged to allow oil to continue to circulate
Check valve	Rubber	Prevents oil from draining from the filter after the engine is stopped
O-ring	Fluororubber (FKM)	Provides a tight connection to the engine

The peculiarity of replaceable elements is in their design. For example, in filters Hengst or Mahle often used corrugated paper impregnated with phenolic resins, which increases the filtration area and extends service life. And in premium models (for example, for Porsche or Mercedes-AMG) can install multilayer synthetic materials, which can withstand pressures up to 20 bar.

Why don't some filters have a check valve?

Cheap filters often do not have a check valve to reduce the cost of production. This leads to the fact that after stopping the engine, oil flows from the filter and oil channels back into the sump. The next time you start the engine, it has to run dry for several seconds, which increases wear. In premium filters (e.g. Mann-Filter or Framm) the check valve is always present.

Operating principle: how a filter cleans oil

The oil filtration process can be divided into several stages:

1. Oil intake. The pump pumps oil from the sump and directs it into the filter through the inlet. The system pressure can reach 3-6 bar (depending on engine speed).
2. Primary cleaning. Large particles (more than 50 microns) settle on the outer surface of the filter element.
3. Deep filtration. Small particles (5-50 microns) are retained in the thickness of the filter material due to its porous structure.
4. Refined oil output. Through the central hole of the filter, oil flows back into the lubrication system.

The key point is work bypass valve. If the filter becomes clogged (for example, during a long oil change interval), the pressure in front of it increases. When it exceeds 0.8-1.2 bar, the valve opens and oil bypasses the filter. This prevents oil starvation engine, but leads to unclean oil entering the system.

Fun fact: some sports cars (eg. Nissan GT-R or Subaru WRX STI) install double oil filters - one for coarse cleaning, the other for fine cleaning. This allows you to increase engine life under extreme loads.

Advantages and disadvantages of replaceable filter elements

Filters with a replaceable element are actively replacing traditional non-separable models, and there are reasons for this:

• ♻️ Savings. The filter housing is reusable; only the cartridge is replaced. It's cheaper by 30-50% at every maintenance.
• 🌍 Environmental friendliness. Less waste - no need to recycle the entire filter, just the filter element.
• 🔧 Ease of replacement. In some models (for example, Ford EcoSport or Renault Duster) the filter housing is located in an easily accessible place, which speeds up the process.
• 🛡️ Reliability. The housing is made of more durable materials than those of cheap non-separable filters.

However, there are also disadvantages:

• ⚠️ Difficulty of installation. The housing must be assembled carefully to avoid damaging the seals.
• 🔍 Risk of counterfeits. Replacement parts are often counterfeited, especially for popular models.
• 💰 High initial cost. The filter housing can cost 2-3 times more than a non-separable analogue.

Important: not all replacement elements are universal. For example, a filter for Toyota Corolla 2018 may not be suitable for Corolla 2020 due to changes in the lubrication system. Always check compatibility VIN code or manufacturer's catalogs.

When and how often should you change the filter element?

The service life of the oil filter directly depends on:

• 🛢️ Oil type (mineral, semi-synthetic, synthetic).
• 🚗 Operating conditions (city, highway, off-road).
• ⛽ Fuel quality (bad gasoline accelerates oil aging).
• 🌡️ Climatic conditions (frost or heat increases the load on the filter).

General rule: the filter is changed along with the oil. For most modern cars, the replacement interval is 10,000–15,000 km or 1 time per year (whichever comes first). However, there are nuances:

Operating conditions	Recommended replacement interval
Quiet driving on the highway (little dust, stable speed)	15,000–20,000 km
Urban cycle (frequent traffic jams, short trips)	8,000–10,000 km
Extreme conditions (off-road, racing, towing)	5,000–7,000 km
Using low quality oil	6,000–8,000 km

⚠️ Attention: If you are using long-interval oil (for example, Mobil 1 Extended Performance or Castrol Edge Professional), this does NOT mean that the filter can be left in place for longer. The filter element gets clogged regardless of the type of oil!

Some manufacturers (for example, BMW or Mercedes-Benz) installed in their cars oil contamination sensors, which indicate the need for replacement. However, these sensors often respond with a delay, so it is better to focus on mileage.

The oil pressure light comes on at idle speed|The oil in the filter is black in color and has a thick consistency|When you start the engine, you can hear the knocking of the hydraulic compensators|The oil consumption has increased without visible leaks|After changing the oil, it quickly darkens (within 1,000–2,000 km)-->

How to properly replace a replacement filter element

The process of replacing a filter with a replaceable element is a little more complicated than with non-separable models, but even a beginner can handle it if you have the tools and instructions. Let's look at the step-by-step procedure using an example Hyundai Solaris (engine Gamma 1.6 MPI):

1. Preparation. Stop the engine and let the oil drain into the pan (10–15 minutes). Raise the car on a lift or use a viewing hole.
2. Oil drain. Unscrew the drain plug on the pan and drain the used oil into a container.
3. Removing the filter:
   • Unscrew the filter housing cover (usually a wrench is required) 27 mm or a special puller).
   • Remove the old filter element and o-ring.

Installing a new element:

• Check that there are no old oil or dirt residues in the housing.
• Install a new filter element and seal (usually included in the kit).
• Screw the housing cover to a torque 20–25 Nm (do not overtighten!).
• Oil refill. Fill in new oil through the neck, check the level with a dipstick.
• Check. Start the engine, let it run for 1-2 minutes and check for oil leaks from under the filter.

⚠️ Attention: Never use old O-rings! Even if they look intact, the rubber loses its elasticity over time and the filter may leak. A new ring is always included with the replacement element - do not ignore this.

If you are changing the filter for the first time, pay attention to element installation direction. Most models have an arrow or inscription on the case "OIL FLOW", indicating the direction of oil movement. If you put the filter in backwards, it won't work!

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Before installing a new filter element, lubricate the O-ring with fresh oil. This will help prevent it from being squeezed out when tightening and provide a better seal.

Common operating errors and their consequences

Even experienced drivers sometimes make mistakes that can lead to serious engine damage. Here are the most common:

• 🔧 Using low-quality filters. Counterfeits of famous brands (Mann-Filter, Bosch) often have a poor seal or low quality filter material. Consequence: oil leaks past the filter, the engine runs on unrefined oil.
• 🛠️ Lid not tightening or over-tightening. In the first case, the filter will leak, in the second, the threads on the housing can be broken. Optimal tightening torque: 20–25 Nm.
• 🗑️ Ignoring replacement when switching to another oil. If you change the type of oil (for example, from semi-synthetic to synthetic), the old filter may not be able to cope with the new viscosity. Always change the filter when changing oil type!
• 🕒 Extending the replacement interval. Some drivers believe that if the oil is still “normal”, then the filter does not need to be changed. This is a mistake: the filter element gets clogged regardless of the condition of the oil.

One of the most dangerous mistakes is using flushing oil without replacing the filter. Flushing flushes deposits out of the engine, which then settle in the filter. If it is not replaced, dirt will flow back into the system upon first start-up.

⚠️ Attention: If after replacing the filter the oil pressure light comes on and does not go out within 5-10 seconds, turn off the engine immediately! This could mean that:

• The filter is not installed correctly (for example, without an O-ring).
• The bypass valve is stuck open.
• There is not enough oil in the system (check the level!).

FAQ: Answers to frequently asked questions

Can the replacement filter element be washed and reused?

No, this is strictly prohibited. The filter material loses its properties after the first use: the pores become clogged with small particles that cannot be washed out. Flushing will only worsen the situation, as dirt particles will be distributed throughout the entire element and will immediately enter the oil when the engine starts. Exception - specialized flushing filters, which are installed temporarily (for example, during a major engine overhaul).

What is the difference between filters for gasoline and diesel engines?

Main differences:

• Soot resistance. Diesel engines produce more soot, so their filters have denser material.
• Working pressure. Diesel filters are designed for higher pressure (up to 10–12 bar versus 6–8 bar for gasoline filters).
• Anti-corrosion protection. Diesel fuel contains more sulfur, so filter housings are often specially coated.

You cannot use a gasoline filter on a diesel engine - it will quickly fail. Replacement is possible, but undesirable due to reduced service life.

Why do some cars have two oil filters?

Double filters are installed on:

• Sports cars (eg Nissan GT-R, Porsche 911), where the engine operates in extreme conditions.
• Diesel engines with system Common Railwhere particularly fine oil purification is required.
• Cars with dry sump (for example, BMW M5), where the oil circulates under high pressure.

Typically one filter is responsible for rough cleaning (retains particles 20–50 microns in size), and the second - for thin (5–10 microns).

How to check if a filter is fake?

Signs of a fake filter:

• Poor quality of printing on packaging (blurred barcodes, errors in text).
• No hologram or protective stickers (original Mann-Filter, Bosch they exist).
• Too light weight (counterfeits often skimp on metal).
• Uneven seams on the body or crooked threads.
• Lack of certificates (eg ISO/TS 16949 for auto components).

The most reliable way is to buy filters from official dealers or trusted suppliers. You can also check the serial number on the manufacturer's website (for example, Mann-Filter has an online service for checking originality).

Is it possible to drive without an oil filter?

Technically possible, but highly not recommended. Without filter:

• Engine life will be reduced by 3–5 times.
• The risk of scoring on the cylinder walls will increase in 10 times.
• The oil will have to be changed every 1,000–2,000 km, as it will quickly become dirty.

The only case when you can temporarily drive without a filter is if it suddenly fails (for example, the housing bursts), and you need to get to a service center. In this case, it is better to drain some of the oil to reduce the concentration of dirt.