Keystone Clock Oil Keystone clock oil is a great mid grade oil for mechanical units. This bottle will last someone forever unless they are working on clocks full time. The smallest drop is applied to anything that spins within something else. Such as the pivot that spins in the outer clock plates. It would be hard to over oil a clock, but it will create a mess down the road. The small drop so it can be seen dropping into the arbor is perfect. This is a 2 oz glass bottle of oil.