There are several possible ways
Classification
There are several possible ways to classify internal combustion engines.
Reciprocating:
By number of strokes
Two-stroke engine
Clerk Cycle 1879 6
Day Cycle
Four-stroke engine (Otto cycle)
Six-stroke engine
By type of ignition
Compression-ignition engine
Spark-ignition engine (commonly found as gasoline engines)
By mechanical/thermodynamical cycle (these 2 cycles do not encompass all reciprocating engines, and are infrequently used):
Atkinson cycle
Miller cycle
Rotary:
Wankel engine
Continuous combustion:
Gas turbine
Jet engine
Rocket engine
Ramjet
The following jet engine types are also gas turbines types:
Turbojet
Turbofan
Turboprop
Źródło: https://en.wikipedia.org/wiki/Internal_combustion_engine
Big end bearings
Lubrication
Diagram of an engine using pressurized lubrication
Wikimedia Commons has media related to Internal combustion piston engine lubrication systems.
Surfaces in contact and relative motion to other surfaces require lubrication to reduce wear, noise and increase efficiency by reducing the power wasting in overcoming friction, or to make the mechanism work at all. At the very least, an engine requires lubrication in the following parts:
Between pistons and cylinders
Small bearings
Big end bearings
Main bearings
Valve gear (The following elements may not be present):
Tappets
Rocker arms
Pushrods
Timing chain or gears. Toothed belts do not require lubrication.
Źródło: https://en.wikipedia.org/wiki/Internal_combustion_engine
Vehicles from abroad
As is well known, very popular in Poland you are purchasing used cars. This involves a much lower cost, so it is no wonder that involved missing. Not less popular cars which were imported from abroad. In countries in Western Europe, many cars are exchanged after a short time of operation, and therefore that their condition is really good, are re-sold in Poland and other countries. Cars that have been used in Germany and France are often much less worn than the cars of the same vintage, which moved on Polish roads. That is why so much interest in such cars.