I was out for a trail ride, some water but not too bad. Buddies CRF450 made out ok. Anyway, on way home the engine seemed to be knocking louder that usual. I drove the rest of the half mile and went home and changed the oil. Lots came out. Filled the oil up, let the bike run for minute, no oil reading on dipstick? Did it again, still nothing. Any thoughts would be greatly appreciated. Dealer said if the oil pump wasn't working it would have burnt up. I don't have a clue why oil isn't getting up to the dipstick area. Thanks (I'm not the greatest mechanic).Bike only has 500 kilometers on it though, and i change the oil religiously with synthetic.