Ive read in several places about how its against the law for a company to make it mandatory to buy their products
instead of another aftermarket company. My friend has a Ford Focus, and he bought a locking gas cap for it from Autozone.
His engine light came on a couple of days later, so he brought it in to the dealership. The dealership looked it over
and told him that since he didnt buy a Ford locking gas cap, he voided his warranty. This sounds like BS. Does anyone know if
there is a webpage that states that companys cannot make you buy their products? Or is this even true?

 

It's federal law that you cannot void a warranty unless you can prove the 'mod' did the damage to the car. Tell your friend to go here and read through that stuff. He should find those words in there somewhere. I hope this helps.

 

Sounds like the typical bullshit that Ford dealerships are resorting to. Just another reason I sold the Contour - Ford's lack of responsible service. I personally know the service manager at my Mazda dealer and that's one of the reasons why I bought my Protege.

 

Have your friend put the original gas cap back on and take the car to a different dealership. The new dealership will have no clue the aftermarket gas cap was on and should fix the issue.