Ok found a few things on the Fleetguard website that might be of interest. First is this... . Q: Why doesn't Fleetguard publish micron ratings for all its filters?
A: Generally this is not necessary. Fleetguard filters are designed to meet or exceed OEM specifications.
Here is another... .
Q: What is the difference between Absolute and Nominal micron rating?
A: Micron rating is the size of particles which are filtered out by filters at a certain efficiency. When this efficiency is at least 98. 6%, we speak about absolute micron rating/filtration. Nominal micron rating is just a commercial trick for all efficiencies lower than 98. 6%, meaning that for the same micron rating (for ex. 10 µ) in the case of nominal rating, not all particles will be captured in the filter as in the case of absolute micron rating.
Q: What's the difference between full-flow and by-pass lube filters?
A: A full flow oil filter is mounted in full-flow, meaning all oil entering the engine is filtered. In full-flow filters, Fleetguard uses cellulose media (40 ? absolute) or upgrade media, such as glass fiber and StrataPore? (25 ? absolute). A by-pass filter is mounted in the by-pass, so approximately 10% of the lube oil flow is passing through this filter. Fleetguard offers "real depth filtration" by means of its stacked disc media. As mean wear particles in engines are in the range of 5 to 30 ?, these particles cannot all be filtered out by the full-flow filter, as these filters would be too restrictive. Therefore, the use of a by-pass filter, such as Fleetguard's LF777, will keep your oil cleaner and result in less wear on moving parts of engines.
Now if you look at the top of
this page you will see under ESXtreme there is a link for a informational video. In this video Fleetguard states numerous times that that their stacked discs
filters out soot and sludge. Well if soot is sub-micron then it would seem to me that the Fleetguard bypass filters must filter down to sub-micron.
In my first post I said that Fleetguard says that they filter 10 microns
at 98% efficiency . This tells me that 98 out of 100 particles 10 microns and bigger are being filtered out. So common sense says that the filter is filtering smaller particle but not at as high of efficiency. Amsoil on the other hand says they filter down to 1 micron. What they
could be saying is 1 out of every 100 particles that are 1 micron will be filtered. Notice I say could, I am not trying to say that Amsoil is out to screw us... . I have their setup on my truck. However with the information we are given I have to say that I like the fact that I
know that 98% of particles that are 10 microns are filtered out rather than my only known from Amsoil is that at least 1% of particles that are 1 micron are filtered.
If you look at the second question about Absolute and Nominal micron ratings. This was what I was referring to when I said that The two companies must use a different method for rating their product.
Now all is not lost. Maybe one of the Amsoil dealers could scrounge up some efficiency ratings and force me to eat some crow.
No prob.
Now the heck with transmission and oil wars, lets step into the 21 century and start a bypass filter war.
Attention: TDR Forum Junkies 
