Noria.com has a highly interesting free "Lube-Tips" e-mail newsletter. Some of you run bypass filters or have made other arrangements to filter engine oil down to single-micron ranges, so you might find a question answered in the latest edition of the newsletter of interest. I received it on Wednesday, 25 February.
Q & A: Can Filters Remove Additives?
"Is there a risk of altering a lubricating or hydraulic oil with 1-micron or submicron filter? For instance, removing the EP additives?"
There are several ways to strip additives from lubricants. Polar aggregate separators (for example, activated alumina), vacuum or thermal dehydration, centrifugation and absorbent depth filtration all present some risk. . . .
There are some classes of additives that can certainly be removed with fine depth media filtration. Many types of lubricants have defoamant additives. These are . . . suspensions in the 5-10 micron range and are filterable. . . .
Efficient 1-micron filters can potentially remove EP (sulfur and phosphorus) additives that are not dissolved as well as suspended solid antiscuff additives.
[--]Mike Johnson, Noria Corporation
This section of the newsletter links to a Noria.com "Learning Center" article, "Using oil analysis to monitor the depletion of defoamant additives" by Jim Fitch. That article is at
http://www.noria.com/learning_center/category_article.asp?articleid=103&relatedbookgroup=Lubrication .
This pertains to finding the causes of excessive foaming and what to do about them.
How much of this is relevant to motor oils for automotive engines is the question. I have long had a hunch that it is possible to "overfilter", and these resources provide evidence. I also question the need to go down to single-digit micron filtration in a car engine, as these particles are rather smaller than typical bearing clearances.
As someone else wrote on another forum long ago, do this thought experiment. Take a marble and put it on a table. Now hold a board an inch above the table. If the board and the table represent bearings, the space represents the clearance, and the marble represents a piece of grit, is it really worthwhile to try to get that marble out? Especially with the evidence that high-filtration systems tend to restrict oil flow--sometimes dangerously, in my opinion?
Food for thought. Your feedback?
Q & A: Can Filters Remove Additives?
"Is there a risk of altering a lubricating or hydraulic oil with 1-micron or submicron filter? For instance, removing the EP additives?"
There are several ways to strip additives from lubricants. Polar aggregate separators (for example, activated alumina), vacuum or thermal dehydration, centrifugation and absorbent depth filtration all present some risk. . . .
There are some classes of additives that can certainly be removed with fine depth media filtration. Many types of lubricants have defoamant additives. These are . . . suspensions in the 5-10 micron range and are filterable. . . .
Efficient 1-micron filters can potentially remove EP (sulfur and phosphorus) additives that are not dissolved as well as suspended solid antiscuff additives.
[--]Mike Johnson, Noria Corporation
This section of the newsletter links to a Noria.com "Learning Center" article, "Using oil analysis to monitor the depletion of defoamant additives" by Jim Fitch. That article is at
http://www.noria.com/learning_center/category_article.asp?articleid=103&relatedbookgroup=Lubrication .
This pertains to finding the causes of excessive foaming and what to do about them.
How much of this is relevant to motor oils for automotive engines is the question. I have long had a hunch that it is possible to "overfilter", and these resources provide evidence. I also question the need to go down to single-digit micron filtration in a car engine, as these particles are rather smaller than typical bearing clearances.
As someone else wrote on another forum long ago, do this thought experiment. Take a marble and put it on a table. Now hold a board an inch above the table. If the board and the table represent bearings, the space represents the clearance, and the marble represents a piece of grit, is it really worthwhile to try to get that marble out? Especially with the evidence that high-filtration systems tend to restrict oil flow--sometimes dangerously, in my opinion?
Food for thought. Your feedback?
