How to Identify & Buy a Good Car Oil Filter

My tip to buying a good oil filter is very easy and can be applied by just anyone! No special skills are required and you don’t have to be a petrolhead to know how to do this.  Oil filters are a critical part to performance & long engine life. Before I offer you this tip, I review the functions of an oil filter and perform a dissection of a good and a lesser quality filter for comparison. If you would rather go straight to the tip scroll down to the last paragraph. >:(

Functions of an Oil Filter:

The key function is filtration of dirt, metal debris, sludge etc from the engine oil. If filtration is not properly done, the unfiltered debris will increase engine wear. So the use of a poorly built oil filter or prolonged oil change intervals will produce more engine wear and subsequently abnormal oil consumption.

An oil filter has 3 key parts amongst others;

  1. Filter paper: does the filtration
  2. Anti drain-back valve: Prevents oil from leaving the filter when the engine is shut off. This ensures that at next start-up, oil is made immediately available to the engine.
  3. Bypass valve: Provides a bypass route under certain conditions to prevent oil starvation in the engine e.g. at start-up (when the oil is cold and thicker), hard acceleration or when the filter material is clogged.

I found a really interesting read on a car’s lubrication system. I owe it the credit for the diagram below. It provides the other functions of all parts of the an oil filter and more. You can get the entire article here

St. Rosemary Educational Institution. "Car Oil & Lubrication System: Overview." http://schoolworkhelper.net/. St. Rosemary Educational Institution, Last Update: 2016. Web. Retrieved on: Wednesday 6th January 2016. http://schoolworkhelper.net/car-oil-lubrication-system-overview/.

Parts & functions of oil filters¹ Credit: schoolworkhelper.net

Dissection & Comparison of 2 Oil filters…
Comparing oil filters

Honda oil filter versus VIC C-809

The 2 oil filters compared here are for the same car. Both are made in Japan. The Honda filter is unused while the dissected VIC C-809 had been used by me. The weight of a filter often gives an idea of its quality. More weight is good as it generally means use of more material.

I start by cutting open the 2 filters, right away the VIC C-809 is more difficult to cut because it has a thicker filter housing shell.

Comparing oil filters

Oil filters cut open (VIC-809-left, Honda-right)

Anti-Drain back valves: Both filters had anti-drain back valves. Your car will have less oil starvation at start-up if an anti-drain back valve is present. Note that not all oil filters have this feature. You can easily confirm the presence of the anti-drain back valve by looking out for it behind the smaller perimeter holes around the screw-on hole of the filter.

Choosing an oil filter

Orange anti-drain back valve can be seen through the perimeter holes of the filter on the right

Next the anti-drain back valve is removed and the heart of the filter compared.

Oil filteration

Filter material compared. Vic-Left, Honda-Right

Filtration material: The image above tells a lot. The pleats of the filter material on the Vic C-809 are more tightly arranged and the height of the filter apparatus higher than the Honda by about 2cm. This means the Vic has more filter surface area and consequently  filter out more gunk from the oil. It will also last longer before getting clogged.

Asides having a higher height, the filter material in the Vic when stretched out was longer. In the picture below, note that about 2cm of filter material had been trimmed off from the Vic because the glue that held it to the end caps was well bonded making it difficult to pull off.

Comparing oil filters

Filter paper in the 2 filters stretched out. Honda-left, Vic-Right

The centre tube on the Vic had more holes offering better flow of filtered oil back to the engine.

oil filter disection

Both centre tubes. Vic-Left, Honda-Right

Bypass valve: Both filters had a bypass valve and the amount of force needed to depress them on both filters felt the same. However the oil pressures needed to open the valves on both filters may still be different.

oil filter bypass valves

The bypass valve on the Vic oil filter being tested

Quick tip for buying a good oil filter

From the above, its quite clear that the Vic C809 is a superior oil filter to the Honda one. You do not have to do all the dissection I did to get a good filter, simply look through large hole on the base of the oil filter to assess the tightness and arrangement of the filter paper pleats. Tight and well arranged pleats are good. Poor arranged and irregular pleats are not so good especially if you use long oil change intervals. Confirm that it has an anti-drain back valve and a bypass valve as well. The bypass valve will present as a stump at the base of the centre filter hole.

example of good filter

Tightly arranged pleats on a good oil filter

Bad oil filter

Loosely arranged pleats on a lesser quality oil filter

Hope you found this useful!

References:
¹ St. Rosemary Educational Institution. "Car Oil & Lubrication System: Overview." [Image]. http://schoolworkhelper.net/. St. Rosemary Educational Institution, Last Update: 2016. Web. 
Retrieved on: Wednesday 6th January 2016. http://schoolworkhelper.net/car-oil-lubrication-system-overview/.

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