The importance of sand in the oil

[marvinlee]

There is a broad awareness that grit in the oil from airborne particles is increases engine wear, but recent factual published studies remain uncommon. "A Study in Sand: Investigating the Damage Done by Desert Dust," by Mark Townsend, and published in"Lubes'N'Greases," February 2012, studies the issue in some detail. Some fragmentary conclusions: The roadside dust samples had an average particle size of 253 microns. The most wear-increasing dust particle sizes are in the 1 to 125-micron range per additive maker Lubrizol. Air filters work best down only to the 100 microns level. The dust comes from both the air and and roadside. Photographs of material wear shows major wear increases from higher dust contaminants in oil. I infer from the study that modern oil and air filters are far from fully effective in removing dust particles (and, by implication, all particles reaching the oil supply regardless of origin).

Lessons? Very few. Dust concentrations, size distribution, and abrasiveness, likely vary widely both geographically and seasonally. The driver has no effective ongoing knowledge, though driving in a dust storm is an obvious insult to oil cleanliness. The study did not examine differences in air and oil filter quality in car brands or filter brands. A fair recommendation is, as the study suggests, to change oil more often if the engine is operated in a high dust environment. This is a very imprecise recommendation since important facts are probably not knowable to the vehicle operator. Perhaps future engines can come with better oil contamination sensors. I was most surprised by the relatively low filtering effectiveness of engine air filters. Perhaps that is why the maker of my car can get by with a 40,000 mile suggested engine air filter replacement schedule. The filter lasts a long time by not doing much.

 

[sciphi]

What about the increasing efficiency of air filters at filtering as they fill up with material? A air filter is the least efficient at filtering when it is brand-new, and the most efficient at filtering near the end of its usable life. But, that increased filtering efficiency comes at the expense of airflow across the filter. Then there's time-based degradation of the filter itself.

Practically, that means using a air filter longer so it can filter better, and then change it right before it impedes airflow excessively or becomes physically degraded. In a sandy environment, that will be necessarily more often than in a cleaner environment.

I suspect that a 40-45k mile air filter change interval is a well-researched compromise between filtration, flow, and physical degradation in a "normal", ie not terribly sandy, environment. A restriction gauge should be used in lieu of the recommendation in sandy areas, and filter changes based on restriction instead of mileage.

 

[friendly_jacek]

Last several times I changed air filters, I was shocked how clean they looked after 30,000 miles. Now, I drive fuel efficient cars, so they breathe relatively little air. Now, cabin filters, that a different story.

 

[4wheeldog]

Where I live, I have found 1/2" gravel on the outside of the air filters, when I have driven in windy conditions. But, with paper filters, no discernible dust on the downstream side. I had some previous experience with K&N filters........Always dust downstream.

(Not to get other than paper filter into the discussion......Just that less than ideal filtration leaves its mark, downstream).

 

[yvon_la]

only way I can think of to prevent dust prom entering a car engine is to create an electrostatic dust collector (probasbly a few in fact)one at the air filter before dusct can actually go in then another in the plastic intake tract.but this also means cleaning more often or at minimum the manufacturer interval but this should effectly prevent less then filter sized particule from entering the engine

 

[yvon_la]

would magnet be ok for electrostatic or not really?any know if the fine wire mesh in big truck(replacing glow plug) in usa is also being used as a electro-static precipitators (basicly dust removal)

 

[dparm]

If sand ingestion were truly a problem, we would not see 99.9999999% of automobile engines passing 200k without serious problems.

 

[richport29]

Originally Posted By: dparm
If sand ingestion were truly a problem, we would not see 99.9999999% of automobile engines passing 200k without serious problems.


Or maybe the norm could/should be 300k if it weren't for sand... Just saying it's a possibility.

 

[FetchFar]

Originally Posted By: marvinlee
..... The roadside dust samples had an average particle size of 253 microns. The most wear-increasing dust particle sizes are in the 1 to 125-micron range per additive maker Lubrizol. Air filters work best down only to the 100 microns level. The dust comes from both the air and and roadside. Photographs of material wear shows major wear increases from higher dust contaminants in oil. I infer from the study that modern oil and air filters are far from fully effective in removing dust particles (and, by implication, all particles reaching the oil supply regardless of origin).
.


I don't see how an oil filter with an ISO 4548-12 rating of 99% for particles greater than or equal to 20 microns (i.e. my Fram ToughGuard TG8765 glass/cellulose blend one) can't scrub out the particles in a few minutes of driving. Sure it will leave about half or so particles of hard silica (sand) from 1 to 19 microns, so that appears to be a damaging size group. ..... Maybe some remember the Mobil1 synthetic oil test in around-the-world driving in a Land Rover where they didn't change the oil until (completely anyway, see http://longitudediscovery.com/TheGreatMobilHoax/index.htm ) the vehicles completed the trip, some of the vehicles anyway.... It does show the sand/grit/dirt building up. I can't tell if they changed the oil filters.

 

[fdcg27]

Originally Posted By: dparm
If sand ingestion were truly a problem, we would not see 99.9999999% of automobile engines passing 200k without serious problems.


...and, this may be because 99.9999999% of the ingested sand goes out the exhaust valves. Only a very small fraction of the ingested sand would end up in the oil.

 

[Shannow]

Originally Posted By: yvon_la
only way I can think of to prevent dust prom entering a car engine is to create an electrostatic dust collector (probasbly a few in fact)one at the air filter before dusct can actually go in then another in the plastic intake tract.but this also means cleaning more often or at minimum the manufacturer interval but this should effectly prevent less then filter sized particule from entering the engine


Fabric Filters are way more effective than (typical ESPs), unless very very long path length and low velocities, sub 10um they aren't that effective.