I have read the posts about the K&N type air filters failing to stop small particles. But does this really harm an engine, since the particles are smaller than the oil film between the engine parts? It seems to me that the amount of Silicon that shows up in oil analysis, is not as important as the size of the particles......
Are Dirt Particles Smaller Than 15 Microns Really Harmful?
- Thread starter TheLoneRanger
- Start date
- Status
Even very small silicon particles will become trapped between the piston rings and cylinder walls and cause abrasive wear of both surfaces. They may be actually broken down into smaller particles by the time they reach the crankcase, or become imbedded in the cylinder wall itself. In many cases they are going to be smaller than your bearing clearances, but you will see significantly elevated iron/chromium levels if you don't keep silicon under control. A human hair is about 100 microns in diameter and the most damaging abrasive particles are generally in the 5-20 micron (um) range, so we are talking about very small stuff. The really big particles will be removed by your oil filter, so it's the smaller stuff you have to watch.
TooSlick
TooSlick
If I remember correctly there are opinions on both sides of this fence. Some say anything under 10 makes no difference. To my knowledge, (like most questions we discuss on this board) there are no scientific studies to substantiate a fact or comment or opinion on whether anything under 10 microns causes wear. Or, if it does, will the engine still go 200,000 miles with not major issues.
Air filters are another trade off. Filters that clean the air best also restrict the air flow. My old Ford non turbo diesel runs a lot better with those low restriction air filters. Any time you can read a book through the element you are paying a price in engine wear. I know the foam or stock pleated paper filters are a lot better at cleaning the air but I hate to give up the performance. A solution would be a big foam filter but I don't know where I would put it. Maybe a small foam filter with a big turbo
People that sell filters that can only filter down to 10 microns will tell you under 10 micron particles are non abrasive. Most abrasives in motor oil are smaller than 15 microns. The full flow filter can remove about anything large enough to see. Forty microns is about as small as you can see with the naked eye. Particles smaller than one micron are non abrasive until they start bunching up into larger particles. I have one filter that can filter down to one tenth of one micron on the first pass. Cigarette smoke is about one tenth of one micron, some diesel soot is smaller than that. Most experts I have read say most engine wear is caused by abrasives in the five to twenty micron range. Some say five to ten microns. I doesn't matter with submicronic filtration.
I think keeping lube oil clean is not so important unless you plan to keep an engine for a long time. A guy in California with a boat told me he expected his Ford Lehman marine engine to last forever. These are the people that really benefit from clean oil, fuel and air.
Ralph
People that sell filters that can only filter down to 10 microns will tell you under 10 micron particles are non abrasive. Most abrasives in motor oil are smaller than 15 microns. The full flow filter can remove about anything large enough to see. Forty microns is about as small as you can see with the naked eye. Particles smaller than one micron are non abrasive until they start bunching up into larger particles. I have one filter that can filter down to one tenth of one micron on the first pass. Cigarette smoke is about one tenth of one micron, some diesel soot is smaller than that. Most experts I have read say most engine wear is caused by abrasives in the five to twenty micron range. Some say five to ten microns. I doesn't matter with submicronic filtration.
I think keeping lube oil clean is not so important unless you plan to keep an engine for a long time. A guy in California with a boat told me he expected his Ford Lehman marine engine to last forever. These are the people that really benefit from clean oil, fuel and air.
Ralph
MolaKule
Staff member
See the Interesting Articles thread, I have some info on particle size vs. wear.
i think this is the one you're refering to..
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=4;t=000059
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=4;t=000059
To say that particles under 15u in size do not cause wear is simply ludicrous - how thick is the film of oil on the upper shell of a con-rod bearing under load? If there are times when the film has been squeezed out and it is down to the barrier, what are these particles doing now?
Maybe the question should be whether these particles exist in the oil under normal circumstances......I say to be sure that they do not, filter your oil well!
As far as a $100 bypass filtration system being unnecessary for a $30,000 vehicle - O.K. save the money for something more practical.
Maybe the question should be whether these particles exist in the oil under normal circumstances......I say to be sure that they do not, filter your oil well!
As far as a $100 bypass filtration system being unnecessary for a $30,000 vehicle - O.K. save the money for something more practical.
Tommy, The hydrodynamic film thickness is somewhere between 1um to 18um ( based on the article Molekule referenced), if we accept the average film thickness as 9.5 or 10 um then the question is how many particles in the range of 9.5 to 15 um are flowing around to cause problems.
If using a good barrier device would the barrier lube be worn or the bearing material itself? During non hydrodynamic conditions.
How large/thick are the micelles that encapsulate wear particles in the disperant?
Why do bypass or finer filtered (smaller sump) engines consistantly show no better wear values than full flow only equipped engines in oil analysis results by independent labs? Larger sump HD diesels exempt.
I agree that if the particles are entering the engine through the induction system the main bearings or rod bearings are a secondary damage site. So air filtration is the key and primary to any oil filtration regardless of efficiency.
If using a good barrier device would the barrier lube be worn or the bearing material itself? During non hydrodynamic conditions.
How large/thick are the micelles that encapsulate wear particles in the disperant?
Why do bypass or finer filtered (smaller sump) engines consistantly show no better wear values than full flow only equipped engines in oil analysis results by independent labs? Larger sump HD diesels exempt.
I agree that if the particles are entering the engine through the induction system the main bearings or rod bearings are a secondary damage site. So air filtration is the key and primary to any oil filtration regardless of efficiency.
I'm sure it may depend on what exactly the particle is of; some will do more damage than others.
With good filters and good oil, and better engines these days, cars are going 2 to 3 hundred thou with no sweat.
With good filters and good oil, and better engines these days, cars are going 2 to 3 hundred thou with no sweat.
Bob, your link in dead.
Microns.... most don't understand the smallness of the micron reference. BTW micron symbol is alt+0181 on your keyboard in case you want to use it.
Bacteria: 2 micron
Red blood: 8 micron
White blood cells: 25 micron
A micron is .000039 inches or 39 Millionth of an inch. What's the nominal clearance of rod bearings?
I see a lot of filters on sites that are usually nominal 19 to nominal 25.
They are full flow and they don't do too bad a job of helping to keep the oil clean.
At the winery where I work, we are concerned with keeping yeast out of wine that is to be bottled with residual sugar. Don't want some wine to go through a secondary fermentation in the bottle and make it cloudy or fizzy, so we use a membrane filter with an absolute value of 0.45µ That takes care of bacteria as well
I can appreciate less than 1 micron filtering, but it might be just a bit excessive. Yes there has/have been studies on micron rating and how it affect wear, so there is really a basis of real information and not "guesses".
SAE testing on a Detroit Diesel (General Motors AC Delco Division) showed an 8x factor at 1µ. But you do get 5x to 6x (times) normal engine life expectancy at 10µ and below.
Now, decide where is your point where you want to save money and where you expect to either retire, or sell the auto you are driving. Is it at 200,000 miles, or maybe 300,000 mile? Only you can venture that guess.
I bought a used 1996 Buick Park Avenue with 147,000 miles on it and everything on it works great.. everything.. and for $1500.00. I want a bypass filter just because (1) I'm a tinkerer, and (2) I want the engine to wear the least amount it can while I have it in my possession these next few years. Keeping the bearings and rings good will keep fuel economy better and oil consumption down, along with any major engine parts replacement.
I live in Michigan. Land of rusty cars. I should do a photo montage sometime with all the rusty framed cars I see at parking lots. I'm not worried about my '96 Buick making 300,000 on this motor, I'm more worried about the rust on the brake lines, rocker panel, underneath bolts, etc. Therein lies my biggest obstacle, not the micron size of oil contamination
Lots of good bypass filters and lots of great oils out there.
BTW I really preferred the old oil bath air filters I remember when I was young. They were messy, but I really think that oil captures more dirt than any throw-away paper element.
Microns.... most don't understand the smallness of the micron reference. BTW micron symbol is alt+0181 on your keyboard in case you want to use it.
Bacteria: 2 micron
Red blood: 8 micron
White blood cells: 25 micron
A micron is .000039 inches or 39 Millionth of an inch. What's the nominal clearance of rod bearings?
I see a lot of filters on sites that are usually nominal 19 to nominal 25.
They are full flow and they don't do too bad a job of helping to keep the oil clean.
At the winery where I work, we are concerned with keeping yeast out of wine that is to be bottled with residual sugar. Don't want some wine to go through a secondary fermentation in the bottle and make it cloudy or fizzy, so we use a membrane filter with an absolute value of 0.45µ That takes care of bacteria as well
I can appreciate less than 1 micron filtering, but it might be just a bit excessive. Yes there has/have been studies on micron rating and how it affect wear, so there is really a basis of real information and not "guesses".
SAE testing on a Detroit Diesel (General Motors AC Delco Division) showed an 8x factor at 1µ. But you do get 5x to 6x (times) normal engine life expectancy at 10µ and below.
Now, decide where is your point where you want to save money and where you expect to either retire, or sell the auto you are driving. Is it at 200,000 miles, or maybe 300,000 mile? Only you can venture that guess.
I bought a used 1996 Buick Park Avenue with 147,000 miles on it and everything on it works great.. everything.. and for $1500.00. I want a bypass filter just because (1) I'm a tinkerer, and (2) I want the engine to wear the least amount it can while I have it in my possession these next few years. Keeping the bearings and rings good will keep fuel economy better and oil consumption down, along with any major engine parts replacement.
I live in Michigan. Land of rusty cars. I should do a photo montage sometime with all the rusty framed cars I see at parking lots. I'm not worried about my '96 Buick making 300,000 on this motor, I'm more worried about the rust on the brake lines, rocker panel, underneath bolts, etc. Therein lies my biggest obstacle, not the micron size of oil contamination
Lots of good bypass filters and lots of great oils out there.
BTW I really preferred the old oil bath air filters I remember when I was young. They were messy, but I really think that oil captures more dirt than any throw-away paper element.
N, The running clearance in the bearings is a lot smaller than the nominal clearance because the crank moves off center because of the load. IIRC, it can be under 10 microns.
Correct. A run through the basic bearing design equations will show that 1µ-3µ minimum film thickness is not unusual.
So a particle 10µ to 15µ better be as round and smooth as a BB, huh?
Make the rod and rod bearings into a sort of grinding machine, don't it!! Please pass the cornmeal
Better use EXTRA good grade oil with correct additives then, and people wonder why cold starts cause wear...
Make the rod and rod bearings into a sort of grinding machine, don't it!! Please pass the cornmeal
Better use EXTRA good grade oil with correct additives then, and people wonder why cold starts cause wear...
It seems to me 600 grit sandpaper has 30 micron particles. The Atomite brand crushed limestone I used to put in vinyl insulation was much smaller than that. We compounded in a Henshel, kind of a 90 horse power blender. About every 25 million pounds, we use the send the bowl out for a new $5,000 1/2'' stainless steel liner. Something kept wearing it and the mixing blades out, and I doubt it was the phthalate diesters. I think the clearances were 2'' or better.
I suspect that many of the particles don't make it into the MFT area. As the oil is "squeezed", many of the particles may be "flushed out". Whatever is left, if harder than the bearing material, will most likely cause wear.
Further, MFT will vary as power, load and RPM changes. Values above are at max power, load, around peak torque RPM.
Further, MFT will vary as power, load and RPM changes. Values above are at max power, load, around peak torque RPM.
Just out of curiosity, how much wear (realitive to other valve train wear) can possibly occure with a 10um particle?
Considering its what.. 40 times smaller then the smallest particle the naked human eye can see?
Isn't there a high possiblity of having casting flaws much greater then that in the bearing just to begin with?
Fishing for an engineer here..
Considering its what.. 40 times smaller then the smallest particle the naked human eye can see?
Isn't there a high possiblity of having casting flaws much greater then that in the bearing just to begin with?
Fishing for an engineer here..
Any parts rubbing next to each other are most likely going to be machined.
Fair enough.
Isn't there a high possiblity of having machining flaws much greater then that in the bearing just to begin with?
Isn't there a high possiblity of having machining flaws much greater then that in the bearing just to begin with?
- Status
Similar threads
