I have a 90hp Yamaha that's 4 years old. The last two years when I've changed the oil and filter, the filter looks like brand new, almost like no oil has gone through it. I had been thinking that it was draining back into the motor while it was sitting.
Now I have a 70hp Yamaha on my fishing boat that I changed oil on last night. It had been sitting in the driveway since Sunday morning, so I assumed any oil in the filter would have drained back into the motor. It didn't. A fair amount of oil came out of the filter when I loosened it up.
Now I'm wondering if my 90hp isn't pumping oil through the filter. I put about 50 hours on the 90 hp every summer. I'd have to believe if it's not pumping oil, the motor would be destroyed by now.