[CarGuy]

The Magnuson Moss act prohibits dealers/manufacturers from requiring service performed at their dealership to maintain warranty coverage unless the service is provided free of charge. Here's a copy of the segment...

"a) Section 102(c) prohibits tying arrangements that condition coverage under a written warranty on the consumer's use of an article or service identified by brand, trade, or corporate name unless that article or service is provided without charge to the consumer.
(b) Under a limited warranty that provides only for replacement of defective parts and no portion of labor charges, section 102(c) prohibits a condition that the consumer use only service (labor) identified by the warrantor to install the replacement parts. A warrantor or his designated representative may not provide parts under the warranty in a manner which impedes or precludes the choice by the consumer of the person or business to perform necessary labor to install such parts.
(c) No warrantor may condition the continued validity of a warranty on the use of only authorized repair service and/or authorized replacement parts for non-warranty service and maintenance. For example, provisions such as, "This warranty is void if service is performance by anyone other than an authorized 'ABC' dealer and all replacement parts must be genuine 'ABC' parts," and the like, are prohibited where the service or parts are not covered by the warranty. These provisions violate the Act in two ways. First, they violate the section 102(c) ban against tying arrangements. Second, such provisions are deceptive under section 110 of the Act, because a warrantor cannot, as a matter of law, avoid liability under a written warranty where a defect is unrelated to the use by a consumer of "unauthorized" articles or service. This does not preclude a warrantor from expressly excluding liability for defects or damage caused by such "unauthorized" articles or service; nor does it preclude the warrantor from denying liability where the warrantor can demonstrate that the defect or damage was so caused."

This doesn't remove the responsibility of doing it, nor proving it was done. Make sure you keep records if you do it yourself or have someone else do it. Keep a small notepad with dates, receipts for the oil, etc. and mileage.