[trenchpilgrim]

I began noticing this about seven or eight years ago when the oil filters I bought changed from official ones to obvious counterfeits (certain pieces were missing entirely + media was much thinner than the real ones). Had to switch to a local auto parts supplier to guarantee the correct part.

[dotancohen]

How did you notice that the media was thinner? On passenger vehicles at least, the filter media is in a stainless steel cup that precludes examination.

[marcusb]

Not always - some passenger vehicle filters have exposed media. An example GM filter: https://parts.gmc.com/product/acdelco-gm-original-equipment-...

My current car has a traditional steel-can filter. I cut those open after oil changes to inspect for debris.

[hangonhn]

BMW at least has the media completely exposed. There is no canister like you might find on Honda oil filters. Basically on BMWs the oil filter housing is permanent. I don't think it's a BMW specific thing. Might be a German car thing?

[tengwar2]

Similar with VAG.

[lazide]

Toyota Tundra filters (at least) are the ‘innie’ pieces, and the cup is a removable/reusable part on the vehicle. A counterfeit would be pretty obvious unless it was at the microscopic level.

[trenchpilgrim]

It was a suzuki with a paper filter cartridge you load into a metal cylinder that is part of the engine. So you can see and feel the media.