Don’t you just hate it when those rubber stopper things pop off inside the oral syringe tubes and you throw them away constantly?  I take ours apart underneath hot sudsy water, then rinse them and leave them to air dry on a towel.  Next I get a plastic sewing thimble and fill it with olive oil and dip the tip of the rubber stopper in the thimble of  olive oil and *zip* it slides right into the syringe tube without getting stuck on the next morning dosage for baby.  Remember to just use a tiny dab... you don’t want to use it so much it’s globby.