Good link-the efficiency for the K&N Select is listed as an equally poor 99% @ 30 microns, Champ manufactured, same filter. Both overpriced fir what you get!I'm seeing 99% at 30u for the 10k filters: ST3614 oil filter
Same rating for the 20k filters: MP4967 oil filter
Where are you seeing 20u? I know it won't have a huge impact on engine longevity, just looking for better information wherever I can.