I poked around and found the link below that talks about the filter testing standard.
The point about flow rates is well taken. Flow rates of filters are designed to be compatible with the intended application, and are dependent on the associated systems. To give a bit more perspective, if you look at the picture I posted in my original post, the OEM TR-1 filter is used across a wide spectrum of Yamaha vehicles, one of which is the YZF R6, a 600 cc in line four cylinder engine that probably red lines around 12,500 rpm. If the filter manufacturers built oil filters that did not flow an adequate amount of oil they would be buying a lot of engines as testing would prove that their oil filters were causing oil starvation related engine failures.
The WIX filters are the only ones that I found with flow rate information of 8-10 gallons per minute. I posted this link above but again here for reference;
Part Details While that flow rate information is helpful, without knowing the flow rate of our engines lubrication system the oil filter flow rate information is not relative. In other words, if our engines only flow 5 gallons a minute it’s non sequitur.
Another important feature is whether or not there is an anti drain back valve in the filter, which both the WIX / NAPA Gold and Amsoil have, others may too but I didn’t look them up. This is especially important for the TR-1 engines and their upside down vertical installation. The 1.8’s are horizontal but the anti drain back is still important here as well. For those that may not understand this, the anti drain back keeps the oil filter full of oil after shutdown so that the oil pump does not have to refill the oil filter before pressurizing the system.
The filter efficiency of the WIX / NAPA Gold is listed as Beta Ratio 2/20=6/20(???), anytime a manufacturer lists data in such a way that only those familiar with the verbiage associated with a testing procedure can know make me go ?…. the WIX lists a nominal particle size of 21 microns. The Amsoil filter is listed as 20 microns at 99% efficiency=easy and transparent.
This last oil interval (100 hours) was the first time I had used the Amsoil filters, I’ve been using Amsoil 10W-40 Marine oil for some time now, and while this may seem subjective it is not, it is an observation, the used oil at the end of this 100 hour interval was markedly cleaner than with the oem oil filters. The used oil with Amsoil filters came out a dark amber, the oil with the oem filters came out coal black.
