I didn't say filters
And OEM is normally an excess stock from manufacturing, caused by price brakes in bulk material purchasing. When you start to talk big numbers, it quite often works out that an overrun of 30% will give you a lower end product price for the 70% that you require. Plus it means that you have a larger amount that meet QC standards. And before you shout the 30% is sub standard, it's not so. Any manufacturer will over produce to drive down costs, and then sell the excess stock off as OEM. Everything that does not meet QC standards is either scrapped or sold off as seconds. Manufacturers work in tons and container fulls, not 1's and 2's.
You don't honestly think that a volume manufacturer would buy paint , for example, by the litre, and pay £150 per litre, like we have to. NO they buy it by the tanker full, the ones that float on the sea, not the silly little things that we see on the road, and as a result they might pay £10 per litre, or even less. It's the law of big numbers, the more you buy, the more a supplier can discount the price and still achieve, the profit that they need to make.
If you don't believe me just look on Alibaba, and look at Android head units for a BMW E39 ( was there last week so I know this one), the prices range from $400 to $200, great I'll have one of those $200 ones, no problem, but you'll have to buy the other 3999 to get that price. And knowing the way that they work, if you were to say to them that you only wanted to pay $150 per unit, the answer would come back no problem that's 10,000 units. Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!