Originally Posted by ken99
No, performing routine maintenance does not void the warrenty.
Mostly the dated receipts with a mileage reference of some sort. I write the miles downs on the back of each receipts and then keep them stuffed in an envelop with the user's guide that came with the truck. Some guys keep logs and there are web pages where you can keep this info recorded. So long as you can verify what you did and when you did is all that matters.
Be careful. These new thermal paper receipts don't keep forever (esp. if they get hot). I'd recommend scanning them into a PDF file as well.
I had one that got shoved into my pocket on a recent business trip and ended up next to the warm battery of my cell phone for several hours. It was almost unreadable by the time I found it.