Oh yee of little faith, prepare to have your mind blown.
This link has been reposted on here thousands of times.
Car owners often get conflicting advice about oil filters. Vehicle owner's manuals, installers, quick-lube operators, mechanics and retail clerks all have different opinions. The reality is that...
www.machinerylubrication.com
"AC Delco Division of General Motors tested diesel engines and found an eight-fold improvement in wear rates and engine life with lower lube oil contaminant levels.
In a related study on both diesel and automotive engines, General Motors reported that “compared to a 40-micron filter,
engine wear was reduced by 50 percent with 30-micron filtration. Likewise,
wear was reduced by 70 percent with 15-micron filtration”. Read that again. That's a lot of motivation for clean oil!"
And there's a chart with the engine mileage vs filtering particle size about 3/4 down the page. Did you think I just made this up?