Typically, no. If you are changing your own fluids and a major component of the powertrain fails, prepare to be asked for proof that you used materials that are approved by the maker of the vehicle that you're driving. Some makers are more picky (most European auto makers), while others are very relaxed.
If you keep a good log of repairs and receipts for purchases, you'll be all set. If you're really worried, buy all oil/filters/fluids at a local Ford service center.
Will come down to the dealer as usual. When my engine blew the place the car got towed to refused to even look at the car because they felt I must not have done maintenance on it because there is no way the engine could fail due to a ford issue (even though a crap load of EBs have gone boom). I had receipts for the oil I purchased and receipts from the shop that did the oil changes. The shop did not put milage numbers on the receipts so the dealer claimed that I could not prove I did oil changes in the required invervals. When I pointed out total milage, time frame etc, they actually told me I could have drive back and forth across country in a few days and then not change the oil till months later, lol.
Needless to say I had it towed to another dealership, they never even asked for proof of oil changes and had a ford approved repair in 24 hrs. So the experience can really be night and day just from one dealer to the next.
No, there's absolutely no requirement that you have to have your maintenance done by a dealer in order to keep you warranty.
However if something malfunctions, and it's proven that you caused it by doing the maintenance incorrectly or choosing the wrong fluid you may get a warranty claim denied.
Agree with all posts, except it doesn’t matter what receipts or legal documents you have - it all comes down to the dealer. You can’t force a dealer to do anything. Life is too short to spend time screwing around with half a$$ people.