This has been posted long ago, I figure I'd bring it back from the dead in a new form.

Source: http://www.ntpog.org/reviews/filters/filters.shtml


Introduction
It has been quite a few years since we began this analysis of filters. The original NTPOG article has generated quite a bit of feedback (both good and bad) regarding the content, test methods, and conclusions. We are pleased to present to you a complete overhaul of our testing.

Many, MANY thanks go out to all the people that submitted filters to us and provided us with positive feedback and suggestions for the study. A special thanks from ALL of NTPOG and I know much of the Honda community goes to Gerhard for taking the time to carry on this study which we in the club simply did not have the time/resources to do.

What this review is: The purpose of this review is to examine the different filters available for Hondas today, including Honda filters themselves. Most people probably don't realize it, but there are at least 3 different Honda filters (with different part numbers, made in 3 different countries! All happen to be very different, as well.

What this review is NOT: This review contains no SAE or ASTM test data regarding filtration ability or flow information. This data changes often (as do the filter designs) and in some cases is not even available (publicly) from a manufacturer. If you are interested in actual filtration information, your best option is to review the data yourself (contact the manufacturers) and do your own oil test/analysis (see below). The information presented here is intended solely to help you determine which filter is right for you from the stanpoint of construction. We also hope to have done the "difficult" work for you as you probably don't want to spend the hundreds of dollars and hundreds of hours that we have dissassembling filters.

NTPOG makes no claim as to the reliability or performance of any filter presented here, nor does NTPOG accept any responsibility for any damage caused by any filter.

Other "Suggested" Reading
We would like to thank Russell Knize for his Mini-Mopar site and his Oil Filter Study page for "Mini Mopars." It was the motivation and source of methodology for my own interest in Honda filters. Please visit his site for Chrysler-specific info or on filters you do not see presented here.

If you are interested in seeing the "original" NTPOG filter review (by Todd Marcucci), you may view it here. Please note, though, that the filter information is VERY outdated. Please refer to Gerhard's data presented in the following review for more up-to-date information.

Finally, we would like to encourage our readers to search the internet for other sites and articles on oil filters and oil filtration as you will find a lot of good information. Some other sites to try:

BobIsTheOilGuy.com
BobIsTheOilGuy.com's Message Board

Background
Well, it's been about a year and a half since Todd Marcucci's original oil filter review was posted on the NTPOG web site. During that time Todd has been collecting various oil filters but didn't have the time to review them. As result of that lack of time he sent them to me!

We're going to go over the same things as in the original reviews, but this time we're going to add some more information about oil types, particle sizes, and lab tests.

The majority of this report is going to go over the physical construction of the filter assemblies. One of the first questions to consider is 'Was the filter physically constructed well?' In order to answer that question we are going to take a look at the basic assemblies found in an oil filter, present a number of measurements, and give you a idea of my opinion of the filter's construction.

The above being stated, it's important for you to understand that I am not a chemical engineer or a expert in the construction of oil filters. I do believe that oil filter construction analysis is not rocket science. There are going to be extremely obvious differences that are going help us determine if a filter is well constructed or something that should never be used in your car.

No claim as to the reliability or performance of any filter reviewed here is made. The information contained in this review is used at your own risk.

What Are the Parts of an Oil Filter?
An oil filter generally consists of 5 discrete sections:

1. The Base, which contains the engine filter seal, mounting threads (outlet hole), and the interior oil filter one-way (anti-drain back) valve.
2. The Can, which encloses the rest of the filter assembly and is roll mounted to the base.
3. The Filter, which contains the medium that removes foreign particles from the oil and is mounted on a sturdy frame.
4. The By-Pass Valve, which is rated for a certain amount of pressure so that it lets oil by-pass the filter when pressure exceeds OEM limits.
5. The Spring, which generally functions to ensure that the filter assembly fits snugly into the base and gasket .

In order:

The Base



The first picture is the external view of the base. The base is (of course) the point that the filter mounts to your engine. At it's center is a threaded outlet hole. Surrounding the outlet hole on the interior is a flexible gasket (second picture) that overlays a series of holes where the oil enters the filter assembly. The gasket acts as a type of one way valve that only opens to let oil in through the holes to fill the assembly. When oil pressure drops (engine is turned off, etc.) the gasket returns to cover the holes preventing the oil in the whole assembly from leaking into the engine and down to the oil pan. The gasket is generally called an anti-drain back valve.

The Filter



The filter assembly is generally a pleated piece of material wrapped around a frame that maintains its structural integrity (as oil flows from the outside to the inside and out the outlet hole). Usually the frame is made of metal, but can also be made of cardboard. The seam of the filter material is generally sealed with a strip of metal that clamps to two pieces together under high pressure. However, it the seam can also be glued together. Lastly, most filter assemblies have a by-pass valve installed in their top, and a large hole at their base that fits into the gasket.

The By-Pass Valve
The by-pass valve functions to prevent a clogged filter from rupturing or, just as importantly, from lower oil pressure. The valve also functions to open during sever oil pressure spikes that happen during periods of very high RPM's. Lastly, the by-pass valve also opens when the oil viscosity is too high (aka the oil has thickened due to cold temperatures, or as a result of to long of an extended drain interval). For this reason is generally a really good idea to use the proper OEM specified multi-grade oil when using conventional motor oils in colder climates (i.e. 5w30 or 10w30 for the Prelude). If you use a synthetic motor oil then this is not a concern all at as almost all brands pump at -40F.

There are a variety of designs for the by-pass valve. Generally, the valve uses a spring loaded design where oil pressure pushes the valve open as pressure builds up from a clogged filter. When a by-pass valve opens it circulates "dirty" oil directly back into the engine to ensure proper lubrication at all times. Usually, the valve is coated in some form of gasket material to prevent leakage.

The Can & The Spring
The can is the piece of metal that incases the entire assembly and is rolled into the base in order to create a liquid tight seal.

The spring is usually either of a leaf or traditional design, and usually sits at the top of the can. Being placed at the top of the can causes the spring to push the filter snugly into the gasket at the base. (I suspect this standard design allows manufactures not to keep tight tolerances in manufacturing of the filter assembly. As such, if the filter varies 1mm to 5mm in height then the spring would simply adjust and keep the filter in place.)

How Do You Take Apart an Oil Filter?
Last time Todd used a Dremel Tool to remove the can from the oil filters so that the insides could be inspected. This time I was able find an oil filter inspection tool that is very easy to use and cuts the base off the filter cleanly.


The tool is fairly simple. You simply place the filter on the round stud, finger tighten the knob, and turn the can with your hand until it pops off (while tightening the knob as the can turns easier).


This page last updated 9/1/01.
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