[ChuckD]

There is a difference in claim and proof. They would first have to prove that the filter caused the malfunction then most of the filter manufactures will also chime in because they warranty their filters and they will spend more to defend their filter than what the actual cost of repair would be. Also according to the Magnuson-Moss Warranty Act in the middle of a warraty period they cannot change the terms of the warranty. Therefor all vehicles under warranty before the change came about will have to be honored.

The Act prohibits anyone who offers a written warranty from disclaiming or modifying implied warranties. This means that no matter how broad or narrow your written warranty is, your customers always will receive the basic protection of the implied warranty of merchantability.

"Tie-In Sales" Provisions
Generally, tie-in sales provisions are not allowed. Such a provision would require a purchaser of the warranted product to buy an item or service from a particular company to use with the warranted product in order to be eligible to receive a remedy under the warranty. The following are examples of prohibited tie-in sales provisions.

In order to keep your new Plenum Brand Vacuum Cleaner warranty in effect, you must use genuine Plenum Brand Filter Bags. Failure to have scheduled maintenance performed, at your expense, by the Great American Maintenance Company, Inc., voids this warranty.

If you ran a Purolator filter in your truck would they deny warranty? even though Purolator makes the MC filter. Its like when Ford wouldnt do anything about the 3.4 SHO engine when they were failing due to the cam sprocket spinning. There is still a big lawsuit over that. With approx. 20,000 cars made and approx. 1150 confirmed cam failures. That is 5.75% and counting.