Drip feed oilers or lubricators were used on early steam and petrol engines and one is shown below on my half size Aermotor engine.
If you would like a free plan to make your own, send me an email and I'll forward it to you.
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The one shown has a 3/4" diameter glass but the design could be scaled down to suit a smaller engine or scaled up for a full size engine.
Video showing how it is made.
I also have castings for sale to build the half size Aermotor engine shown above.
Details of the engine can be seen by clicking Here
