In general, these are substances that reduce friction when placed between two surfaces with relative motion.

There are lubricants with different grades and viscosities, although their functions have a lot of similarities:

• Reduce friction between two metal surfaces.
• Protect mechanical components from wear and corrosion.
• Clean and cool engines.
• Act as a sealant between the segments/pistons and jackets in order to prevent gas leaks from occurring inside the combustion chamber.

• To reduce friction between two metal surfaces.
• To protect the mechanical parts from wear and corrosion.
• To clean and cool them.
• In engines, the lubricant acts as a sealant between segments/piston and sleeves, avoiding compression leaks.

• Most oils on the market (gasoline oil or diesel engine oil, mineral oil or synthetic oil), can be mixed between them. 
• However, since mixing two qualities of different oils reduces the quality of the oil, it is not recommended.

• Although many lubricants are formulated to be used in both gasoline engine oil and diesel engine oil vehicles, some lubricants are designed especially for gasoline engines, and others for diesel engines. 
• It is important to ensure suitability prior to use.