# Help calculating filter efficiency based on micron rating?

#### Ed_Flecko

Most of the time, I see filters stating their efficiency based on the ISO 4548-12 testing method with a micron size of 20.

I'm looking at a Mahle filter which states, "...The filter can even remove up to 95 % of tiny particles just 10 ìm in size"... Source: https://bit.ly/3fWduIO

So I can compare the Mahle cartridge to other brands, is there a way to extrapolate what the filter efficiency is at 20 micron particle size (i.e., like most of the other brands)? Is there a way to calculate this? I'm sorry if this is an obvious and easy "conversion".

Thank you!

Ed

#### ZeeOSix

I don't see where they say 95% removal of 10 microns in the link you gave above. Every oil filter has it own unique efficiency vs particle size curve, and it's not a linear curve. In the case of the Mahle, it could be 95% @ 10u and 98~99% @ 20u. Just like with the Ultra, it's rated at 99%+ @ 20u but according to Motorking (Jay) it's 80% @ 5u. You would need at least 3 or 4 data points to get an idea of what the efficiency vs particle size curve looks like.

#### Ed_Flecko

I don't see where they say 95% removal of 10 microns in the link you gave above. Every oil filter has it own unique efficiency vs particle size curve, and it's not a linear curve. In the case of the Mahle, it could be 95% @ 10u and 98~99% @ 20u. Just like with the Ultra, it's rated at 99%+ @ 20u but according to Motorking (Jay) it's 80% @ 5u. You would need at least 3 or 4 data points to get an idea of what the efficiency vs particle size curve looks like.

Thank you!

Ed

#### ZeeOSix

Here's an example of various oil filter efficiency vs particle size curves. You can see it's really not very linear on the top and bottoms ends, and more so linear in the mid range.

#### Ed_Flecko

Here's an example of various oil filter efficiency vs particle size curves. You can see it's really not very linear on the top and bottoms ends, and more so linear in the mid range.

View attachment 25686

Cool...thanks! That's good information.

Ed

#### Donald

If you want to get the small particles you need a bypass filter. No full flow will do the job. Now the related question is do you need to get the small particles to have engine last 200K miles?

#### Farnsworth

It says that under "a new filter medium." You can't really extrapolate and say its's data because it isn't. That's a very high number. Notice is says up to 95%. It also states the fibers are plastic, polypropylene probably like Ford Racing oil filters Seems to be the latest thing. It really is a judgement call as to what one wants to buy.

#### ZeeOSix

If it's 95% @ 10u, then it's oblivious a higher % at 20u and a lower % at 5u. Knowing how oil filter efficiency curves typically look for full synthetic media, I'd say that it's pretty close to what the Ultra would come in at (99%+ @ 20u and 80% @ 5u).

#### kschachn

If you want to get the small particles you need a bypass filter. No full flow will do the job. Now the related question is do you need to get the small particles to have engine last 200K miles?
Not for the engines I own. In fact I've gone double that.

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