The problem with manufacturer power train warranties is that some manufacturers honor then with no problems, others look for an excuse not to pay. Some will claim that not changing your oil and getting the service recommended in the owners manual voids your warranty even if the problem is not directly related. Some will make you document that the did the service, on time, before they will honor the warranty. If you can't then you are out of luck.
I have not had much trouble getting work done. I do however do all of the maintenance, often at the dealer.