Oil filter OEM BMW or AC DELCO

RockAuto sells AC Delco oil filters for $9. AC/D dexos 5-quart for $19 and one single quart for $4.

I buy 6 quarts of Pennzoil 5w30 full synthetic and an AC Delco filter for like $38 from Walmart.

In my area I usually buy my Mobil One full synthetic at Walmart in the 5qt jug for roughly $22, use what I need (my vehicle uses litters ...) My Delco filter is like $6.

My lovely girl friend has a 2 door BMW 1997 325i. It's a very pretty car with 176k miles on it. We drove it all over and one day it hit me, when was the last time the oil was changed? She thought her parents maintained it, but after some digging the oil hadn't been changed in 1 1/2 years and possibly 30k miles. I pulled the filter out and it was worse than this, and just fyi BMW filters like these do it kinda often from what I have read.

Then engine had 2.5 out of the 7 quarts it is supposed to have. (poured the oil in a 4 quart jug to see). I have absolutely no idea how it lasted so long. It was a ticking time bomb. So after 6 quarts of oil and the seventh being sludge cleaner, the engine has no more ticks and runs very well.

For oil filters I feel like the ACDelco filters are pretty low quality and there are many better options. Mobil and K&N oil filters are available at Walmart for $10-15, made in USA, and seem to be much better quality.