In this system, A small quantity of lubricating oil is mixed with a fuel (mostly gasoline). The oil and fuel mixture is introduced through the carburetor. The gasoline is vaporized and oil which is in the form of mist enters the cylinder via the crank base. The droplets of oil strike the crank base, lubricate the main and connecting rod bearings and the rest of the oil lubricates the piston, piston rings and cylinder. The system is preferred in two stroke engines where crank base lubrication is not required. In a two-stroke engine, the charge is partially compressed in a crank base, so it is not possible to have the oil in the crank base.
The various advantages are:
No oil changes and reduced maintenance requirements
Reduced lubricant consumption (up to 70 percent compared to sump lubrication)
Lower friction and reduced bearing temperatures
Mist delivery pressure blocks entrance of contaminants
Less wear and increased life of machine elements
Lower capital costs
This system is simple, low cost and maintenance free because it does not require any oil pump, filter, etc. However, it has certain serious disadvantages.
2. Wet-sump lubrication system: