You don't have to use "genuine Honda" parts, unless Honda wants to supply them free of charge. A manufacturer can not require you to use any particular brand of part as a requirement for warranty, unless it's free, because they would then have exclusive parts and you don't want to think what the prices would be. It's the law. I purchased one of the little books you can buy for keeping gas mileage records and just use a line everytime I do something or buy parts. One yearly book lasts the lifetime of the vehicle doing it my way, and every repair is listed in order. I keep receipts for all parts and oil I buy in a seperate file at home. If you have a warranty claim, in order for the manufacturer to deny repair, they have to be able to prove you caused the damage intentionally or that by using that non-genuine part you caused the problem. Now, if it was obvious that the oil had never been changed because it was coming out in clumps, they might be able to hang it on you, otherwise I don't think you will have a problem. Ask Hal before you purchase the warranty, if in doubt.