keep the rod at flexed slightly forwardly to avoid contact with the wiper element thus the film which is necessary to provide a proper reading of the quantity of oil in the crank case or oil compartment will remain because the film resulting from the rod 15 penetration of the oil when the rod is fully seated with the stop 31 against the top of the tube 20 will not have been erased by the wiper element it will be seen in this operation that the operator 39 s hands need not make contact with any of the oil covered portions of the ullage rod nor is it necessary for the operator to have paper a cloth or any other similar element handy in order to wipe the rod when it is first removed as previously explained oil wiped from the rod by the wiper element which is in excess of that which can be retained by the wiper element will drip back down the tube 20 into the crank case thereby preventing it from becoming smeared on the exterior surface of the engine however oil which remains and accumulates on the wiper element 15 may work its way back to the top portion 11 and drain down into the trap 17 since this oil will have been exposed to the dust and grit normally present in the engine compartment it is important that it not reenter the crank case the presence of the trap prevents this and the holes 18 are insurance against its accumulation in the trap despite the presence of the opening 13 particularly are the.