So I decided to cut open my oil filter to see what it looked like on the inside. (duh)
(^That was my reaction.) That's what the Anti drain back valve looked like when I took off the cover. And in the next pic you can see how the rubber valve has seated into the wrong position all this time. The rubber itself was stiff but not brittle.
Now onto the filter element.....yeah, you can clearly see a sizable hole (giggity) there.
The Endcap had cracks around the inner side, the pic below shows the largest ones.
The spring was still very stiff and in good condition.
The car is an 2006 Daihatsu Terios. The oil this filter was put with was M1 15w50 because the owners manual said That I could use it for this climate. BUT while I was using this combination of oil and filter, every cold start the engine had a lot of valve noise like starting the car with an empty oil filter due to a bad ADBV like seen in the previous pics. Not to mention that the oil was a little on the thick side. This oil was drained after about 5k miles because one morning I checked my oil and and it was black as [censored] and below the add line on the dipsick. I changed the oil to Valvoline Synpower 10w30 and a Wix Filter. The valve noise is virtually gone at ANY start up.
But I have a feeling that this filter is probably a fake because I've heard on here that if the filter says 'Made in Japan' than the filtering material would be different than this one. Correct me if I'm wrong. The end of the filter WAS wrapped in plastic when it was new.