Common misconception. Under the Magnuson–Moss Warranty Act the warrantor cannot require that you use "their brand" of oil. "Warrantors cannot require that only branded parts be used with the product in order to retain the warranty. This is commonly referred to as the "tie-in sales" provisions." 15 U.S. Code § 2302 - Rules governing contents of warranties note (c)keep in mind that motorcycles under any type of factory, or extended warranty have language about maintenance and its best that you use exactly what the manufacturer recommends, and use only manufacturer branded oil and filters (and keep the receipts). I know its silly, but doing otherwise gives them the easiest reason to void your warranty.