As a supplier of filters to the parts divisions of some major car companies there are a number of comments that are correct. WB Ute knows that many are similar or identical filters and just branded or numbered differently. Often they are the same filter renumbered when a model changes and often one car brand is the same as a different brand. Ryco often list one part number a suiting a range of vehicles.As Damienengland knows some factories produce the same filter under different car company or aftermarket packaging. Reputable brands regardless of car company or aftermarket usually comply with regular testing to ensure conformance. Having a bad batch and doing a "recall" is a costly exercise that people want to avoid. The initial testing and sample submissions are very rigorous, and those records are retained for a long time. There are so many factors involving engine operation that people are quick to point to the filter first. Often it is traced to some other problem. It is like a car where everyone can make their own choice of brands. It is often the case of you get what you pay for. If you have an expensive machine or engine why try and cut a few dollars off your investment by buying something that is not 100% suitable.