This is a report about a work in progress that started out to be testing and reporting on bypass oil filters and wound up being a lot more ‑‑ but that is often the case with works in progress

 

All of my observations about bypass oil filters have been on products manufactured by Gulf Coast Filters (GCF).  It should be noted that I have no financial interest or connection with Gulf Coast Filters in any way and have no interest in whether you purchase anything because of these reports.  The information is from my observations on my equipment.  Its purpose was for my own benefit.  I just share the information I have gathered for any use ‑‑ or none ‑‑ you wish to make of it.  I have learned that there are many different manufacturers of bypass oil filters.  Among the names that jump

out are Enviro, Filmax, Premo Plus, TF Purifiner, and the one that I have observations from, Gulf Coast Filters.  I have made one phone call to one other filter manufacturer, Fleetguard, and they also make a bypass oil filter.

 

At the outset, I am happy to report to you that all of my experiences in this field indicate that the competition is civil.  They all think theirs is the best, but they don't shout that the competitor's doesn't work.  They all agree on the basic premise of operation and make their case on the special merits of their own product.  Isn't that a delight?

 

It is of historical interest that bypass oil filters were around before full flow oil filters.  I had a client whose father made him equip a fleet of trucks with bypass oil filters in the '30s when no other oil filters were on the engines.  It seems that the bypass filter concept died when it was thought that the, then, new full flow oil filters did the entire job.  It had a rebirth when extended oil drain periods became desirable in industry.

 

For those who were not around when this thread was active a few months ago, a little introduction is presented below.  In addition the prior post about the Portable Oil Analyzer will give some more additional background on this subject.  Old hands who have heard more about this subject than they need can just hit the delete button.

 

 

The Bypass Filter Concept

 

The bypass oil filter operation is to circulate ALL the oil through the full flow oil filter and circulate approximately 10% of the oil through the bypass oil filter and return it to the crankcase.  Generally the oil goes to the full flow filter first and then the bypassed part goes through the bypass oil filter before returning to the crankcase.  The concept is that the full flow filter must always pass all the oil to keep from starving the engine.  Time has shown that to do that, the full flow filter can only take out the large size debris.  There remains a lot of small stuff that is very harmful to the moving parts of the engine.  The bypass oil filter can be designed to be much more efficient than the full flow oil filter because no

catastrophic harm results if the bypass filter gets stopped up.  It just stops producing its extra benefits.

 

Two broad classes of oil filters are "Surface" and "Depth."  A full flow oil filter is almost always a "Surface" filter, and a bypass oil filter is almost always a "Depth" filter.  In surface filters, the oil goes through the filter more‑or‑less perpendicularly to the filter medium.  The filter gets to work on the oil in one pass at the surface of the filter.  In depth

filters, the oil must pass through a filter medium of considerable depth B it must stay in contact with the filter medium a relatively long time.  It  should not be surprising that the full flow, surface, oil filters filter in a general range of 10 to 30 microns, and the bypass, depth, oil filters filter in a general range of 1 to 5 microns.

 

There is an additional class of bypass, depth, oil filters that I'm aware of ‑‑ "Absorption."  That is to say, that the filter medium in these filters is made of material that will absorb moisture.  That material is often paper and in the case of GCF, either paper towels or toilet paper.

 

When Does The Oil Need To Be Changed

 

The whole bypass oil thing came about because of the desire of industry to extend the oil drain interval in commercial operations.  Changing oil in commercial operations is a direct deduction from the bottom line of the profit and loss statement so there has been a lot of interest in safely extending the drain interval to improve profits.  If that situation did not exist, you'd not be reading this now.  Our industry is just not large enough to support the research and manufacturing necessary to keep this issue alive.

 

When do you need to change oil?  The short answer is when it gets dirty. That can be extended to a more informative answer.  The oil should be changed when the contaminants are higher than desirable, and/or the additive package is depleted more that desirable, and/or the viscosity of the oil is unsuitable.

 


Most of us non‑commercial diesel engine users change oil at the hour interval recommended by the engine manufacturer or at least once each season.  That may produce the desired results, but there is a better way. The better way is to change the oil when laboratory oil analysis shows it is time to change the oil.  That may mean changing the oil after 50 hours, 100 hours, 400 hours, or never.  For starters, changing oil this way may save you some money ‑‑ the laboratory I use charges $12.00, and the direct oil and filter cost to change my oil is just a little under $40.00.

 

 

The Value Of Oil Analysis

 

Saving a little money and/or labor by using oil analysis may be a small incentive to use laboratory oil analysis to determine when to change oil. But the real benefit of doing it that way is that the oil analysis will give you a history of the health of your engine.  Concentrate on "health."  The oil is the lifeblood of the engine and most of the terrible things that are going to happen to your engine will be forecast by the condition of your engine oil.

 

The first oil analysis may tell of many immediumte problems, but the real value is a continuous record that gives the trends over time.  It is great that we don't need to interpret the laboratory results ourselves.  The laboratory will do that for us just like our doctor interprets the analysis of a blood sample.

 

There has been a heated thread, on the list, about the difference in dependability of single vs. dual engines.  Laboratory oil analysis history, and corrective actions as indicated, are quite likely the most important things you can do to increase the mechanical dependability of your engine(s) ‑‑ single or dual.

 

 

The Problem With Laboratory Oil Analysis

 

Say What?  CaptnWil has just tried to sell laboratory oil analysis, and now he is saying there is a problem with that very thing.

 

The problem is that the information we get from laboratory oil analysis is only valid for the instant in time when the samples are taken.  It gives us enormous amounts of information at the moment of taking the sample, but we are in the dark until the next oil sample is taken and the laboratory analysis is done.  For those who use a boat less than 200 hours per year, it is likely that only one laboratory oil analysis would be made in a year. That is certainly more information than is normally known, but it is still a long time between getting valuable information.

 

The solution is to supplement the laboratory oil analysis program with a Portable Oil Analysis reading after each day's operation as indicated in a previous post.

 

The information we need is gained in a digital nature.  Just like increasing the clock speed in our computers gets us information faster, using a Portable Oil Analyzer each day will keep us informed about the health of our engines on a daily basis.

 

 

Where Are The Bypass Oil Filters

 

Take special note that bypass oil filters have not been mentioned at all in the last four sections.  It is not necessary to install a bypass oil filter to have most of the knowledge that can come from a formal program of both Portable and Laboratory Oil Analysis.

 

It has been argued that boats that are used as little as most pleasure trawlers can't justify the expense and trouble to install a bypass oil filter system.  Another argument has been that since the normal life of a trawler diesel is longer than the owner will keep the boat, bypass oil filters should not be considered.  The conclusion of both arguments is to just change the oil often and all will go well.  Until my preparation for Trawler Fest in Melbourne Beach, I would have agreed with that argument entirely ‑‑ if the oil analyses procedures described above are followed.

 

In the next post, I'll report some observations that were not only surprising, but shocking as well.  Those observations will give you some more information to make a judgment about this whole matter.

 

CaptnWil

 

SUMMARY FOR NEWCOMERS


There is a large body of unbiased technical reports and laboratory oil analyses to verify that Gulf Coast Filters (GCF) bypass oil filters keep engine oil in serviceable (almost new) condition for an unlimited time in commercial and industrial equipment that runs long and hard under adverse conditions.  The sources agree that keeping the oil in new condition reduces the wear in the engine materially and increases the life of the equipment. Among those sources of information are Shell Oil Company and The North Carolina Ferry System.  More details are in the first reports that should be in the archives.

 

Recently, I have personally seen and listened to a Detroit diesel engine equipped with a GCF bypass oil filter that is about to, or has just, passed 1,000,000 miles with one oil change.  The oil change was done by mistake.

 

All of this came from equipment that used GCF filters.  While the information I have and my experience is with this brand equipment only, I would not be surprised if similar results can be obtained from other depth, absorption‑type bypass oil filters.  I want to emphasize that the purpose of this report is the concepts presented and not in a brand of equipment.

 

All of those results were from equipment that runs hard and long.  Often it runs at near full load.  The information was from commercial and industrial equipment and that means that the equipment operation is vastly different from the way we operate our recreational trawlers.  I could not doubt the truth of the facts, but I wondered how all this related to our type operation.  The tests I conducted were intended to answer that question.

 

 

INITIAL RESULTS

 

A paper towel bypass oil filter was installed on my trawler's main engine, and a toilet paper bypass oil filter was installed on the generator.  Oil analyses were made before installation of the filters and at more frequent intervals than normal to check results of the Portable Oil Analyzer (POA). My tests were almost non‑events.  The filters improved the condition of the oil and it remained almost like new.  For example, after 302 hours on the filter and 468 hours on the oil in the ADC Ford main engine, the laboratory oil analysis was so good that the lab manager asked if I had made a mistake about the engine hours.  The POA reading was 1.4.  Remember that the POA says change the oil at a reading of 4.6.  302 hours ago the POA reading was 1.2. The results on the generator are even more spectacular.  I have absolutely no doubt that these things work.

 

 

START AND STOP

 

One of the things that concerned me was how our "Start‑and‑Stop" driving impacts the operation.  Most of our boats sit at the dock much more than they travel.  Often our boats sit at the dock for a whole winter.  Most of us have a concern about what happens to the inside of our engines during long lay ups.

 

The POA was a great help since I could get a result after each day's operation.  In my engine the readings increased the first day after a long lay up.  Then they decreased and leveled out.

 

We started our winter cruise after a 3‑month lay up and put 198 hours on the engine.  The POA readings went from 0.95 to 1.2 to 1.8 and then during the cruise decreased to 1.4.  During this cruise we ran almost every day.  You should understand that anything under 2.0 is almost new oil.  All of these readings are excellent, but the most interesting thing is how being underway is better that being at the dock ‑‑ in more ways than one!  Of special note is the fact that the 3‑month lay up didn't do any harm to the oil that was not corrected by the bypass oil filter.  The POA didn't indicate changing the oil when putting the engine back in service.  In all of this, laboratory oil analysis supported the results of the POA.

 

 

BASIC CONCLUSIONS

 

1. POA analyses and laboratory oil analyses are important tools that can provide valuable information in the operation of any engine. 2. Installing a bypass oil filter can greatly extend your oil change interval, and will reduce the wear in your engine materially.

 

 

CONCLUSIONS BEFORE TRAWLER FEST

 


The benefits of using POA and laboratory oil analyses are valuable in all situations.  The real question to answer is does the benefit justify the expense and trouble of installing a bypass oil filter considering the way you operate your boat?

 

Initially I felt one should consider installing the bypass filter if he used his boat more than 200 hours a year and wanted long life.

 

 

SOMETHING HAPPENED ON THE WAY TO TRAWLER FEST

 

Remember that this is still a work in progress and I discover new (to me) information all the time.

 

One of the features of the GCF filter is that the used medium can be inspected when it is replaced.  Even though all the readings indicated that the filters did not need to be changed, I wanted to display them at Trawler Fest in the presentation.  I planned to arrive at Trawler Fest by boat and change the filters the day before the presentation.  Circumstances developed that made it necessary to return home on the boat and travel to Trawler Fest by auto.  I had a lot of equipment to display so I decided to take the pickup with a Cummins 6BT engine in it.

 

Before leaving home, I changed the bypass oil filters in both the main engine and generator.  I was shocked.  Right there on the top of both used filter elements was some debris ‑‑ debris big enough to see.  The stuff on the main engine bypass filter was as big as large fleas on a dog.  The stuff on the generator filter was white and smaller.

 

Both of these engines are almost new.  The oil and full flow oil filters have been changed exactly as recommended by the manufacturer up to the time of installing the bypass oil filters.  The generator came with a special "break‑in" oil filter that was twice the size of its normal full flow oil filter.  Where did that stuff come from?  I don't know, but it scares me to

think that it came through the full flow oil filters.  Charlie Sims of GCF says that it is normal to find such stuff the first time the bypass filter is changed, but if it is ever seen again, there is a big problem.  That's a comfort for my engines that are now protected with the bypass oil filters, but what about my other engines?

 

I installed the Cummins 6BT in my pickup with the intent that it would be the last pickup I would ever have and the last pickup engine I would ever buy.  Was the same kind of junk running around in my 6BT?  I don't know, but I decided to install a bypass filter on it for protection.

 

While thinking about this, I looked at the specifications for the 6BT and discovered that the oil bypass valve opens at 60 psi.  I have a real mechanical oil pressure gauge and started observing it during the operation of the engine.  In outdoor temperatures between 50 and 75 F., when the engine is started, the oil pressure increases and remains near 70 psi at

moderate RPM for a considerable period of time.  Then the oil pressure decreases and stabilizes at about 50 psi.  During the time the oil pressure is above 60 psi, part of the oil circulated through the engine does not go through the full flow oil filter.  My oil is 15W‑40; suppose it was straight 40 weight?

 

I don't have a specification indicating when the oil bypass valves on my other engines open.  But I wonder what kind of unfiltered junk is circulating in them at engine startup.  The generator adds the complication that upon startup, the engine runs at full operating speed ‑‑ 1800 RPM.  It is commonly held that major wear occurs at startup.  Could the circulation

of unfiltered oil be a part of that?

 

These two discoveries, for which I have no answer, have changed the equation for me.  I now believe that installation of a bypass oil filter should be considered for any engine from which long life is desired.  I would not put one on an auto I was going to trade every 3 years, but I would put one on a boat I expected to keep for 10 years.  Because of the startup situation, a bypass oil filter may be more important to recreational start‑and‑stop trawler use than to the commercial long‑running use.  I will not argue with you if your conclusions differ from mine.

 

During the summer, I'll put a lot of miles on the 6BT under major loads. Since it is an engine used in a lot of trawlers, I'll give brief reports of the results of the bypass filter operation from time to time.

 

CaptnWil