Since the earliest days of the automobile in late 19th century, the dominant powerplant has been the reciprocating piston, spark-ignition Otto-cycle, followed by the compression-ignition diesel. Those ...

It would have been revolutionary: an internal combustion engine without oil. And it might have worked. But lots of real-world issues got in the way.

SAE Transactions, Vol. 23, PARTS I and II (1928), pp. 145-150 (6 pages) COMPROMISES are necessary in designing a piston, sacrificing the quality of least importance under the given conditions.