According to the manual for my '97 XR600 I should add (2.06) quarts when changing oil and filter. But when I followed the directions to the letter it took (2.5) quarts to get the level to the upper hole on the stick. Thats almost a half quart more than the book says. I let the engine get up to operating temp then shut the engine off and immediately checked the level. All the while holding the bike level just like the manual says. And no, I didn't screw in the stick. What gives? Is there something I'm missing here?