A few decades ago service stations carried jars of oil right next to the pump. It wasn't unusual for the attendant to add a quart to your engine while he was filling your tank and cleaning your windows. It would be an extraordinary circumstance to see someone with their hood up adding oil at a gas pump in this millennium. I am confident that service advisors are taught/told a new and broader understanding of the terms "normal" and "can't replicate". I am also sure service advisors deal with customers that are less than sincere. In my situation, I was polite, persistent and kept detailed notes. At oil change time, I made sure my truck was filled to the full line, not above or below. (My dealer did the changes.) When I needed a top-up between changes, I had my local quick-lube add the oil. This way I got a dated receipt with the exact quantity added. It took time but I believe it was the service advisor that was the key in getting my truck fixed. Bringing in two or three receipts of significant amounts of oil being added between scheduled oil changes moved his perception from normal to unusual. A lengthy powertrain warranty adds comfort but don't procrastinate in your efforts to deal with such matters. Time and miles have a nasty habit of slipping by quickly!