The High Density Polyethylene (HDPE) Nalgene bottle I suggested is impervious to gasoline and petroleum products. It is the same polymer material that gas cans and gas tanks are made from. The transparent Nalgene bottle are polycarbonate plastic (AKA, Lexan) which may not be 100% compatible with motor oil additives.I think the narrow-mouth Nalgene is the way to go. Most, maybe all, have an oz. and ml. scale printed on the side. You can also get them in a harder transparent material.