There is no more simple way to illustrate this than to state we have to acknowledge the difference between efficiency and effectiveness.
Something can be very efficient, but not effective. Other things can be effective, but not efficient. Some things can be both. Other things can be neither.
The most important thing to understand is that efficiency and effectiveness are NOT dependent upon each other; they can exist in a mutually exclusive environment.
It's nearly time for March Madness, so let's make an example of basket-ball ....
Your favorite player might be really efficient at shooting three pointers; say 50% from behind the line. But his effect on the game depends upon TWO things; the shots taken and his accuracy.
My favorite player might be really efficient at shooting from the stripe; say 85% at the foul line. But his effect on the game depends on those same two things; how much he gets fouled and his accuracy.
If you're player takes ten 3-pt shots, his efficiency would contribute 15 points to the game. (50% of 30 potential points = 15 pts scored). But if he only takes 2 attempts all game, it's probable he'll only add 3 pts.
If my player takes only 3 attempts at the foul line, he'll only contribute (90% of 3 = 2.7) pts per game, on average. However if my guy gets to the line 10 times, he's going to contribute 9 pts.
This is all obvious, right?
The point I make is that EFFICIENT filters do not have nearly as much EFFECT today, because other things have made filtration less relevant. (Filters are not meaningless, but capture ratio is not as important as it once was.)
The GM and Bus studies only show that heavily contaminated systems can see wear improvements when vast, wide disparity exists in the filtration choices, in extended (or outright deleted) OCIs.
But
those conditions are not relevant today. Again, the following things make highly-efficient filtration meaningless:
- the TCB is now understood how it affects wear
- engines today do not self-pollute with soot the way they did decades ago
- oils are formulated to be much more robust; they handle contamination so much better now, and also resist oxidation to a much greater degree
- design of equipment has been refined
- manufacturing capabilities have been greatly improved
The point is that highly efficient filtration cannot make a significant impact when other things are controlling wear with greater effect.
Filtration efficiency was important many years ago because the sumps contained large amounts of contamination, and the oils were not able to deal with that resultant contamination as well, and the equipment was not made as well. But all that has changed. Sumps are just a lot cleaner now because engines just run so much cleaner in the combustion process. Equipment is designed and manufactured much better now, so it not only wears less, but is less susceptible to what little contamination is present. And lubes have more additives to deal with what remains, and reduce the ability of things like soot to grow in size.
Your point, Zee, that there will be less particulate in the system is salient, but it's not relevant. A highly efficient filter will catch more stuff, but there's so little for a FF filter to catch in a normal OCI that the EFFECT of the EFFICIENCY is indistinguishable in real world wear rates. Any particle that is fairly large will be caught by most any decent filter. Small stuff is not caught by any normal filter. The reality is this:
Your player whom is really good at 3-pt shots is not going to win the game because he's not getting a chance to take many shots at all; other players have reduced his ability to score, because they are denying him the ball!
I agree that finer filtration makes for less particulate in the system.
I disagree that highly-efficient filtration has a major effect today.
And there are tens of thousands of used oil analysis to prove my point.
What was relevant from yesteryear is moot today.
Once a sump is "clean enough", making it "cleaner" does not necessarily make it "better", if "better" is defined as less wear. Your definition of "better" is "cleaner'. My definition of "better" is "less wear". You focus on the inputs, whereas I focus on the outputs.
This thread actually started back in 2002. A LOT of things have changed since then.
As you state, Zee, we will agree to disagree.
I'm OK with that .... no harm, no foul
