Bypass Oil Filters - Keep or Remove?

FF said:

"I was just wondering if they're worth the inconvenience."

Just look at your oil.

Is it almost clear or black black stuff loaded with carbon & fines?

An engine with clean oil should last longer.

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In a diesel engine, unless it's a brand new engine, the oil stays clear for only a short time.

So a visual check of the oil tills you little about the true condition of the oil.

OK, the consensus seems to be "keep 'em." I like the theory that if they're getting hot, they're not plugged.

BTW, these things take closer to a gallon of extra oil each, not a quart. If nothing else, having that extra gallon of oil circulating in the engine can't be a bad thing.

I think I'll check out Blackstone. I've just put 150 hours on the mains in less than a month and a half; this should be a good baseline. I usually change the oil at 100 hours or less, if I haven't gone out much that season. I guess if the results come back and say my main bearings are shot, I'll have something else to keep me awake nights

CaptTom said:

I think I'll check out Blackstone. I've just put 150 hours on the mains in less than a month and a half; this should be a good baseline. I usually change the oil at 100 hours or less, if I haven't gone out much that season. I guess if the results come back and say my main bearings are shot, I'll have something else to keep me awake nights

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If you think you will use the analysis a number of times, there is a significant incentive to prepay. I do about 6 tests a year between boats and truck, so it's worth the savings.

Ted

I've used bypass filters and centrifuges for about 50 years. Properly used, they greatly extend engine life. Bypass filters work on the principal that the slower oil passes thru the filter, the more dirt is captured. Standard full flow filters don't capture dirt much below 30 microns. Bypass filters often capture dirt to 1 or less microns.
What really determines an engines overhaul needs are ring and sleeve wear. Rings carry oil up the cylinder for lubrication. Sleeves/cylinders have small scratches (cross hatching) that allows for oil travel. Once the cross hatching is worn away, the sleeve and rings wear quickly. Dirt carried in oil causes the wear. No dirt, little wear.
I'm old and have owned or operated dozens of engines. Almost every engine I owned had a bypass filter and went 2x or more times the usual overhaul hours. Now I centrifuge the oil and capture particles well below 1 micron. I have the oil analyzed and change at 500 hours. The oil is still transparent.

I would love to see any documentation from 3rd party investigations on whether bypass filtering extends engine life.


Seems like it would...but the actual recommendations from engine manufacturers don't seem to be coming to the forefront supporting this.


If they are I have missed it and would enjoy the read.


Any documentation beyond thread entries?

There's a lot of info on the web. Some industry sources and many selling bypass filters. Engine manufacturers have no real interest in doubling engine life unless their competitors do so. They'd rather sell parts, short blocks or new engines. Every ship or large commercial boat I've been on either has a centrifuge or bypass filters. Most industrial users, oil rigs, mine equipment, large trucks have them, too.
I don't sell bypass filters. Use them or not.

Sure there is a lot of info on the web..too much to sort out unless you have a link to something substantive from a third party comparison...otherwise it is white noise from just anyone and makers of bypass filtering.

Understanding Engine Oil Bypass Filtration

""With bypass filtration, the flow rate can be greatly reduced, allowing for a much smaller pore size while retaining a normal pressure differential. The result is much cleaner oil being returned to the sump. Smaller soot suspension and polar insolubles that are not controlled by the full-flow filter can now be taken out of the system. When combined with a full-flow filter, bypass filtration offers the benefits of lower wear generation rates, lower oil consumption, higher combustion efficiency and longer oil life.

In a case study performed by General Motors and published by the Society of Automotive Engineers (SAE), it was determined that engine service life could be extended eight times when 5-micron filtration is implemented vs. the standard 40-micron filtration."

psneeld said:

Sure there is a lot of info on the web..too much to sort out unless you have a link to something substantive from a third party comparison...otherwise it is white noise from just anyone and makers of bypass filtering.

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PSN

You have summed it up, white noise. The difficulty with posting a dealer supported treatise is exactly that, advertising and marketing claims and promises.

An additional question to the OP's is "Why do recreational marine engines fail?" Assuming one does the recommended routine oil and filter changes, engine failures due to lubrication would be way down the cause list.

What does in a non marine dirt moving engine can indeed be filtration, air filtration. Having lived and worked through more than half a century of dirt moving diesels spanning many hundreds iof engines, lubrication related failures were a result of low oil levels, broken gears in oil pumps and oil cooler failure.
During my career the opportunities to do in house tests, studies and view supplier provided history was quite informative.

The whole game plan was to keep the wheels rolling. Extended oil life was one thing, quicker oil changes another. But this type of up time improvement was a cooperative effort between the suppliers and end users. Everybody had skin in the game.

Nothing the matter with more oil filtration, but if it comes with faith based belief rather than facts then I say BS. Especially when the word rare is used to define oil change intervals.

By pass filtration seems to me to be fuel polishing by using the engine's oil pump instead of a dedicated pump.
But I know little about it. I don't polish and I don't by-pass. But re the OP if I bought a boat w a good by pass filter I'd keep it and maintain it.

2 Different views,

#1"In a diesel engine, unless it's a brand new engine, the oil stays clear for only a short time.

So a visual check of the oil tills you little about the true condition of the oil."

#2 "I have the oil analyzed and change at 500 hours. The oil is still transparent. "

#3With ONLY a bypass filter my 6-71 lube oil stays clear and golden past 100 hours.

If your bumping into them and the heat hurts, can you pin an old cotton towel around them?
Should help a lot to keep from being burned.

kapnd said:

Modern oil filters are a product of much re$earch and years of experience.
Do you really think Bounty designs their product with oil filtration in mind?
The extra 2 qts is not very green.
A bypass oil filter allows unfiltered oil to circulate in your engine, not a good idea.
I would never install anything but a premium oil filter.

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Using a bypass filter ABSOLUTELY does not allow unfiltered oil to circulate. While some folks do not believe bypass filtration works or is worthwhile, this statement is wholly inaccurate..

sunchaser said:

Surely you jest.

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Jest? Surely? Science denier?

Lepke said:

I've used bypass filters and centrifuges for about 50 years. Properly used, they greatly extend engine life. Bypass filters work on the principal that the slower oil passes thru the filter, the more dirt is captured. Standard full flow filters don't capture dirt much below 30 microns. Bypass filters often capture dirt to 1 or less microns.
What really determines an engines overhaul needs are ring and sleeve wear. Rings carry oil up the cylinder for lubrication. Sleeves/cylinders have small scratches (cross hatching) that allows for oil travel. Once the cross hatching is worn away, the sleeve and rings wear quickly. Dirt carried in oil causes the wear. No dirt, little wear.
I'm old and have owned or operated dozens of engines. Almost every engine I owned had a bypass filter and went 2x or more times the usual overhaul hours. Now I centrifuge the oil and capture particles well below 1 micron. I have the oil analyzed and change at 500 hours. The oil is still transparent.

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Times about a hunded.

sunchaser said:

Especially when the word rare is used to define oil change intervals.

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You may not like the word but that doesn't change the fact that by combining good bypass filtration and oil analysis, you may find you can greatly extend your oil change intervals.

And thus, may rarely have to change your oil.

Especially the 100 engine hr per year crowd......

FF said:

2 Different views,

#1"In a diesel engine, unless it's a brand new engine, the oil stays clear for only a short time.

So a visual check of the oil tills you little about the true condition of the oil."

#2 "I have the oil analyzed and change at 500 hours. The oil is still transparent. "

#3With ONLY a bypass filter my 6-71 lube oil stays clear and golden past 100 hours.

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Yes very different. In #1 I'm speaking to an older, like most here have, diesel engine with no added bypass filters.

I can't say I've seen older engines keep their oil visually clean for all that long after a change.

But other folks experience may be different.

psneeld said:

Especially the 100 engine hr per year crowd......

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Exactly!

But that crowd are really not who would benefit from it. It's the high use folks who really put hours on their engines and may travel to places where disposing of used oil properly, and perhaps ethically, can be a PITA.

Especially high use gensets. That's where I really like to use bypass filters combined with synthetic oil.

Plus I think there is more to contaminants in the oil than just hours run.....

As sunchaser said...in some conditions, special air filtering probably has as much impact.

I still would like to see exactly what engines and how they benefit....no doubt there is a nice benefit for high hours/tough conditions....but I need to do some research out of curiosity.

psneeld said:

As sunchaser said...in some conditions, special air filtering probably has as much impact.

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Plus there is the wet salty air that can get into an engine back through the exhaust when the engine is sitting unused.

"A bypass oil filter allows unfiltered oil to circulate in your engine, not a good idea."

Today ,,Almost all bypass filters are ADDED to an engine .

So the existing Full filtration of chunks and metal stays in place.

MY 1950's era DD 6-71 is an exception in having only a bypass filter , however the oil samples come back fine.

All of my marine engines came with full flow filters but they also came with centrifuges or bypass filters as built. It was quite obvious when getting oil analysis as well as when you performed an oil change that he systems play a role.

So I've been doing some reading on spin on bypass filters and have some questions:

1. If you're not going to extend time between oil changes, do they make a significant difference long term?

2. If using a spin on filter type, does the filtration improve with time (caking), uniform throughout the filters life, or degrade over time?

3. The most common spin on filters have absolute ratings (98% filtration) of 15, 8 or 2 microns. If the goal is to remove harmful particulates as opposed to extend oil change intervals, is 2 micron filtration significantly better than 8 micron?

Ted

catalinajack said:

Jest? Surely? Science denier?

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Science denier? Hardly. I've been involved with dozens of very large engines where bypass filtration is supported and recommended by the the OEM. This better filtration is part of an in depth program to extend base engine life. As mentioned by many here oil analysis with factory support as data is accumulated go hand in hand.

But and a very big but, the purpose of optimum oil filtration and analysis is to extend engine life not increase service intervals. For the 100 hour per year lazy boat owners, rarely changing your oil because you have a Gulf Coast filter is indeed bad science.

For those who enjoy using a search engine look up SOS for some interesting data on oil filtration. Further, Fleetguard has a good article on bypass filtration fact and fiction.

A few interesting side notes, cold starts are the hardest thing on engine moving parts. That is why gensets, commercial diesels in tugs, mining fleets etc get such long engine life. Second, oil filters break down over time and not only lose their filtering ability but release trapped particles into the oil flow. Thirdly, if you are seriously using an oil analysis program, an oil analysis on the clean oil is essential.

Don't take it from me though, or other anecdotal mutterings you read on the Internet. For oil and filter change intervals read what Cat, Cummins, Deere, northern Lights, MAN etc state in the books they give you. Many of these books are written for engines where bypass filtration is OEM with good filters.

Like the dentist, once per year or more often as hours increase prevents decay. Last but it least, you may be in for an eye opener when looking up costs for accurate techniques for measuring 5 micron particles and assaying same. It is a science well beyond a 50 buck quickie.

O C Diver said:

So I've been doing some reading on spin on bypass filters and have some questions:

1. If you're not going to extend time between oil changes, do they make a significant difference long term?

2. If using a spin on filter type, does the filtration improve with time (caking), uniform throughout the filters life, or degrade over time?

3. The most common spin on filters have absolute ratings (98% filtration) of 15, 8 or 2 microns. If the goal is to remove harmful particulates as opposed to extend oil change intervals, is 2 micron filtration significantly better than 8 micron?

Ted

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Good questions Ted. I have been told by experts that oil filters are short lived due to hot pressurized organics eating up the cellulose. Thus adding another conundrum to lazy boaters who like to ask, "I only ran my engine 20 hours last year, do I need to change oil?"

I think the concept of a bypass system is good. In medium to larger size engines, they are equipped with them. On very large engines, centrifugal purifiers are used.

On my Cummins 450, the oil filter has a bypass element tucked into the bottom, and a venturi provides the flow motive. Pretty neat. Larger Volvo's have a separate bypass element. But many commercial duty engines have no bypass at all and seem to have very long lives.

The concern is not whether a bypass is there, but how well it is engineered. I have seen systems added where the plumbing was definitely sub par, and one had a fitting fail that dumped the sump. Engine wrecked, not just worn out. That did not work out so well.

The other concern is the filtering: I suppose, but don't really know, that super tight filtration might eliminate some compounds that were added to the oil intentionally. That is a question for the tribologists.

Or that the filter media, such as paper towels, might degrade and release something bad into the sump. Paper towel makers probably do not spend much time considering hot lube oil when developing or changing their product.

The oil formulation, filtration system, and the engine itself need to be engineered as a system. Start adding things without considering all the effects, and testing, and you can introduce other risk factors.

"cold starts are the hardest thing on engine moving parts. That is why gensets, commercial diesels in tugs, mining fleets etc get such long engine life"

On cruise ships that are basically genset powered the units are plumbed to stay warm when off, and cab go from start to loaded in under 90seconds.

I'm not a believer in the "cold start is bad for engines" theory. My VW diesel car is 16yrs old and is driven daily. At least two starts are cold daily, and often a few more are warm starts. Let's say two starts cold per day. This is ignoring the warm starts, which there are probably as many.

That's 11,680 cold starts. Include warm starts and that is around 32,000. Last time I looked at the cam while doing a timing belt, all looked perfect. I don't know what the bottom end looks like as it has never been opened up. I did an oil sample a couple years ago and it was very good. No block heater, no oil additives. 242,000miles which is about 6000hrs depending on what avg speed is picked.

If starting the engine caused the majority of wear, this thing should be a basket case. It is not. Well, my starter is beginning to drag a bit, but that is understandable considering it is original.

I think the reason most large prime movers last so long is by being heavily built, with a modest specific output, and engineered with longevity as a primary goal. Long run periods can't hurt, either. And there is usually an engineer monitoring them often, keeping up with optimal care and feeding.

I'm in the land of Chesapeake Bay watermen. Cold starts are a way of life. If the creek ain't froze, turn the key; it's time to go to work. It's rare to see a block heater on a waterman's boat. 15,000 to 20,000 hours isn't uncommon for their engines.

Ted