Particle Size Question

[Merkava_4]

<span style="font-family: 'Verdana'">Let's say a grain of sand is in your engine oil. Which particle size in microns would be safe to go through your engine?</span>

 

[ZeeOSix]

It won't go through your engine if you use an efficient oil filter.

 

[Merkava_4]

<span style="font-family: 'Verdana'">What if the particle is smaller than 20 microns and goes through the filter; is it safe at that size?</span>

 

[Nick1994]

Originally Posted By: ZeeOSix

It won't go through your engine if you use an efficient oil filter.

With Tearolators you could throw a rock in the oil and it'd go through Ok fine it wouldn't get past the pickup screen. Maybe that's all we need? Like the air cooled VWs. I vote all the Purolator lovers to volunteer to swap out their oil filters with screens.

 

[Nick1994]

Originally Posted By: Merkava_4

What if the particle is smaller than 20 microns and goes through the filter; is it safe at that size?

I think, say, a Fram Ultra can filter smaller than 20 microns, it's 99.9% efficiency rating is just that, a rating at that micron size. So at 15 microns maybe it's 85% efficient and at 10 microns it's 75% efficient (I totally made up those numbers BTW).

 

[Leo99]

I think Merk's question more along the lines of how much damage can 1 grain of sand cause should it get past the oil filter. And at what particle size would you no longer worry about engine damage?

 

[ZeeOSix]

Originally Posted By: Nick1994

Originally Posted By: Merkava_4

What if the particle is smaller than 20 microns and goes through the filter; is it safe at that size?

I think, say, a Fram Ultra can filter smaller than 20 microns, it's 99.9% efficiency rating is just that, a rating at that micron size. So at 15 microns maybe it's 85% efficient and at 10 microns it's 75% efficient (I totally made up those numbers BTW).

Per Motorking, the Ultra is 80% @ 5 microns.

 

[ZeeOSix]

Originally Posted By: Leo99

I think Merk's question more along the lines of how much damage can 1 grain of sand cause should it get past the oil filter. And at what particle size would you no longer worry about engine damage?

All the papers about engine wear vs particle size say that particles 25 microns and smaller do the most damage because they are able to get into the tighter clearances in an engine (journal bearings, etc). The SAE "bus study" did show that a more efficient oil filter kept the oil cleaner, and cleaner oil resulted in less engine wear. There have been lots of talk about this in various threads in this forum.

 

[Garak]

Originally Posted By: Merkava_4

Which particle size in microns would be safe to go through your engine?

The real question is what do you define as safe? If your desire is to absolutely minimize abrasive wear no matter the cost, you can run Fram Ultras or their equivalent and bypass filtration and spend all kinds. Or, you can run an ordinary filter and still get hundreds of thousands of kilometres out of an engine and be sick of the car long before it's dead.

 

[ZZman]

A grain of sand is 100-10000 microns. Huge in terms of particle size in oil. There will be many particles below 20 microns in the oil. It is a balance between flow and filter efficiency. I believe 5-20 micron sizes are the most damaging.

 

[StevieC]

Particles larger than 20 micron are the most damaging to an engine. Below 20 micron are less damaging until you get down to 1-2 micron range which it would take a lot of to do damage. This is why bypass filtration is so much better than conventional spin-on filters at 20 micron because it filters down to 1-2 microns. That's how they drastically extend engine oil life.

 

[Kira]

The OP's question was vaguely phrased at best. When "sub 20 micron" particles go through lubrication systems the ones shaped like sugar cubes do the most damage. The ones which resemble spheres or velvet covered footballs cause the least.

 

[Donald]

Bypass is cost effective for diesel engines that go many hundreds of thousands of miles and have large oil sumps. So oil changes are several hundred dollars. A decent filter and reasonable OCI will allow a normal car engine to not be what causes the car to go to the boneyard. Filtering so that the engine is in pristine condition when the car goes to the boneyard makes no economic sense.

 

[goodtimes]

1/4 micron appx., below 1/2 micron, other larger sand particles will scratch but will eventually wear down into smaller particles. Particles imbed in soft metals and then become grinders until they wear down or are torn out of the matrix. They cut diamonds with copper discs, and diamond saws with sintered edges use the same idea, imbed the particle to present it to the surface to be ground or cut.

 

[Ducked]

Coincidentally (?) this came up just recently. Shannow posted a good overview paper for diesel engines. http://infohouse.p2ric.org/ref/31/30453.pdf The bulk of the wear is caused by particles below 10 microns. Since there are situations (cam lobes, gears) where the parts are in boundary lubrication with zero clearance, there is no particle size too small to cause wear.

 

[bullwinkle]

If it was small enough to go through the pickup screen AND the oil filter, it would likely imbed itself in a soft bearing surface in the engine, causing a particle streak and potentially a groove in the rotating part. That's why I NEVER prefill oil filters-too risky, what if some random chunk of junk is in that unfiltered oil? I would guess even a jobber filter would catch something as big as a grain.

 

[Ducked]

Originally Posted By: bullwinkle

If it was small enough to go through the pickup screen AND the oil filter, it would likely imbed itself in a soft bearing surface in the engine, causing a particle streak and potentially a groove in the rotating part. That's why I NEVER prefill oil filters-too risky, what if some random chunk of junk is in that unfiltered oil? I would guess even a jobber filter would catch something as big as a grain.

Should be OK if you prefill from the outside in, surely?

 

[MasterSolenoid]

To put it in perspective, .001 inch is equal to 25.4 microns

 

[Linctex]

A strand of human hair is about 100 microns wide A red blood cell is approx 8 microns in diameter

Originally Posted By: MasterSolenoid

.001 inch is equal to 25.4 microns

If a filter can get 99.999% of anything larger than .001" (25 microns) - long engine life will be secured.

 

[JohnnyJohnson]

Originally Posted By: ZZman

A grain of sand is 100-10000 microns. Huge in terms of particle size in oil. There will be many particles below 20 microns in the oil. It is a balance between flow and filter efficiency. I believe 5-20 micron sizes are the most damaging.

Yes they all damage some just damage at a slower rate its just like course sandpaper vs very fine sandpaper they all wear some just slower.