1, lubricating antifriction: between piston and cylinder, are present between the spindle and bearing a rapid relative sliding, to prevent excessive wear of parts, you need to build two oil film between the sliding surfaces. There is sufficient oil film thickness will be relatively spaced sliding surface of the part, so as to achieve the purpose of reducing wear.
2, cooling down: Oil can be re-distributed oil equipment the sump tank to the air to help cool the engine.
3, cleaning Clean: good oil to the engine parts carbides, sludge, wear metal particles circulating back through the sump, the oil flow through, wash the parts produced work surface dirt.
4, leak-proof seal: Oil can be formed between the piston ring and the piston ring, to reduce gas leakage and to prevent outside contaminants to enter.
5, rust and corrosion: lubricants to prevent water adsorption surface of the part, air, acid substances and harmful gases oil processing with the part.
6, the shock buffer: When the engine cylinder port pressure rose sharply, suddenly intensified pistons, piston debris, connecting rods and a large load on the crankshaft bearing, the load transmitted through the bearing lubrication, to withstand the impact load plays the role of buffer .