My son rides a 2005 CR85R, bike is solid runs perfect but burns gear oil for a short time after oil change. Honda recommends 0.58 qt which is 18 ounces. If I put 18 ounces in the bike will burn oil until it has about 12 ounces. I tried putting 16 and 14 ounces in and burned a little as well. If I put 12 ounces in it will not burn any. Anyone ever seen this?????