Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 15, 2025 ...

Bypass oil filters

August 26, 2013, 06:05:20 pm

I've been running with a bypass oil filter installed on my Cat 3208T and it is slowly cleaning up the carbon in the oil.  Does anyone use this set-up?  What I wonder about is if there is an equilibrium level where the filter doesn't keep up with the amount of carbon put in by combustion and it just levels out there.  How important is it to clean it all out of the engine?  Carbon deposits are very small (1micron?) and it doesn't seem as though there would be alot of wear caused by that.  Thank you  ----  Fritz

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Re: Bypass oil filters

Reply #1 – August 29, 2013, 03:08:24 pm

You will know when the by-pass filter loads up when the housing does not get hot and tells you it's time for a new cartridge. 
Depending on which brand of oil you use (I recommend Rotella) has a great deal to do with how clean your engine runs. 
 
Notice that I am not suggesting which oil you choose to use and keep in mind that it's not too positive to change labels for this reason.

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Re: Bypass oil filters

Reply #2 – August 29, 2013, 05:52:12 pm

An oil's job is to keep soot particles in suspension.  Their size precludes any effect on engine wear.  They would only cause a problem if the recommended oil change interval was greatly exceeded, causing soot particles to precipitate out, forming sludge which would clog oil passages.

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Re: Bypass oil filters

Reply #3 – August 29, 2013, 07:37:28 pm

Thanks for the info.  ----  Fritz

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Re: Bypass oil filters

Reply #4 – August 29, 2013, 08:46:02 pm

I added a 2 micron bypass lube filter last year,after I was unable to find the particle size that the stock cummins oil filter with internal bypass filter would remove.  With timely oil changes and only 10 or 15,000 miles a year I know the engine will last longer then me, But I do like clean oil it's the life blood of the engine. SAE technical papers 881827,881825 and 95255  state that 70 to 80%  of all failures and wear in diesel engines are from particles of 10 microns or less and that controlling particles in that size range will result in significant reductions in component wear. Engine wear test DDA 6v-53T performed by AC Delco concluded that control of particles in the 3 to 10 micron range had the greatest affect in reducing engine wear. Gam

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Re: Bypass oil filters

Reply #5 – August 30, 2013, 07:27:14 am

Fritz started the discussion talking about soot.  Carbon particulates are soft.  Metal particles below 10 microns can indeed cause engine wear, though again in our application these engines should outlive us given normal maintenance.  On the other hand, I have read of bypass filter systems using remote mounting having hose failures with subsequent engine failure.  Not good.

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Re: Bypass oil filters

Reply #6 – August 30, 2013, 09:46:29 am

Amsoil started marketing their by-pass filter system decades ago (sold and installed a bunch of them).  If you don't care to change your oil and are using a quality synthetic, I know of no other method of keeping oil clean.  Discussion will come concerning the viability of changing oil, which is good, but this bridge has been crossed years ago and the question concerning by-pass filtration is well documented. 
By-pass filters and synthetic oil systems (if you care to go to the expense) and have the available room for the install, work very well.
As for a by-pass system with conventional oil, yes it also works but not with the success with using synthetics.  I like NEO FWIW.
Do I use one?  Not in the last few decades.  I like going under and looking.
Last by-pass filter I installed was on a D13000 Cat in my Dads 65' shrimp boat.  We did not change the oil, only the by-pass filter when it got cold.  The engine is still running (I'm told, but not in the same boat BTW).
Oil stayed clear and passed sample test every 200 hrs.
pc

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Re: Bypass oil filters

Reply #7 – August 30, 2013, 10:28:57 am

And there is far less soot with the new Ultra Low Sulfur Diesel than there was with the old diesel!

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Re: Bypass oil filters

Reply #8 – August 30, 2013, 10:29:34 am

As per Bob the oil  and many other reports diesel soot is a submicronic particle { less then 1 micron } that is very abrasive. But since it's submicronic it can't cause much wear. The problem is that the soot particles will try and join together and become larger. Good engine oils have dispersent additives to prevent this but they can be depleted.With timely oil changes you shouldn't have a problem with soot in your lube oil , but it can build up in your system.  Another problem is the % of soot in the oil of any size.  Less then 3% is OK ,but more then 4% and wear can occur. Particle counting is though by many to be the single most important test used in oil analysis for extended oil change intervals. My coach is in the carport more then on the road and I think that is hard on the engine. To me a diesel likes to run and the cleanest possible oil helps it to do just that. I was able to install a bypass filter that removes 98% of an particles over 2 microns in size for less then $100. Any system can fail but I used braided stainless steel hose with threaded end { no hose clamps } and there good for 3000 PSI.Gam

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Re: Bypass oil filters

Reply #9 – August 30, 2013, 11:36:07 pm

For my Caterpillar 3126B I use an OPS oil purification system that has a 3 micron bypass filter and a heater to burn off the acids. I use Rotella T6 full synthetic oil. I send oil samples approx every 150 hr and they do an extensive analysis on oil for many things including soot. The check also checks for oil additives. If the correct hoses are installed per installation manual I do not forsee any leaks in this setup. Many over the road trucks use this system.
Bill

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Re: Bypass oil filters

Reply #10 – August 31, 2013, 01:35:42 am

I find it so interesting that many people pooh pooh the idea of a good quality synthetic when it has been proven time after time in far more strenuous machines than our Foretravels etc. Why do they buck this trend?? I figure it comes down to a few dollars extra and that blows my mind when the front end cost is so high. If it was a jet engine there would be no discussion, period!!
Sorry, but I go by the way the tests show what is good for our baby. Amsoil and the 2 micron bypass filter they make.
John H

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Re: Bypass oil filters

Reply #11 – August 31, 2013, 10:02:54 am

have three 1981 honda CB900C motorcycles. The best one by far I bought from five years ago from a gentleman that had it 16 years, not sure when he started using synthetics (crankcase and gear case, which are separate on this machine, unlike many motorcycles), but at 51,000 or so miles, it is by far the best running, highest compression and strongest of the three. Made me a believer, even at $45 an oil change, which I do annually.

In the bus however, I just but in Rotella and change it annually. Seems to fit manufacturers recommendation and no matter what we do, I doubt the bus will ever get to 500,000 mile, although the engine easily would. So I keep the money and put it in diesel fuel. Guess I could put in one of these fancy systems, but just seems like overkill. WOuldn't mind making the investment if the oil change savings paid it off over 5 years, since I plan on keeping the coach longer than that. (Apologies to Dave Head....)

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Re: Bypass oil filters

Reply #12 – August 31, 2013, 10:51:11 am

No worries for me! That's about the time I plan on being debt free and looking for a new coach.

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Re: Bypass oil filters

Reply #13 – August 31, 2013, 01:02:17 pm

I have a bypass filter system and I like it, even Cummins has them. I use Rotella 15w40 engine oil because the engine was designed to use it and run for ever. I change my oil and lubricate the chassis every 7,000 miles or every year as per the MFG. For me synthetic engine oil is just over kill in MY diesel and how I use it. I use synthetic in my front hubs , differential , trans,  and even for the  stern drives on my  boat {twin Yanmar 360 HP with Rotella oil and 1MPG}. My Foretravel doesn't  have a jet engine  thats high speed rotor turns at 15,000 RPM for hours on end, I had a Honda CD 900 in 1982 and If I remember it was about 4,400 at 60 MPH and just over 9,000 RPM tops and air cooled { turned it in for a 1986 Ninja 900 } so to  me synthetic is the oil to run in both. What oil you use in your coach is after all up to you , and all the brand names are better now that just a few years ago. For me cost is a consideration with a lot of things but $50 a year more for engine oil isn't one of them I just don't see a need.  Gam 

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