I follow the prescribed method of checking the oil level. Warm engine then check level when bike is vertical. I also always check after a ride. I find the level is good when warm but when I check cold it is usually low, barely on the dipstick. I usually top up when I see it is low when cold. I have added about 1 litre of oil in about 10000km over and above the regular oil changes. I change oil at a little less than 5000km intervals. Is this normal??