Lub oil properties

Oil is selected to improve the engine operation and reduce the wear down rate and hence the maintenance cost of the machine.

Alkalinity

• When fuel burns, the fumes carry sulphuric acid which can cause acidic corrosion. Four stroke engines, the main lube oil is responsible for piston and liner lubrication; alkalinity of lube oil is important for controlling acidic corrosion.
• For two stroke engines, separate grade of lube oil is used as cylinder oil and its alkalinity depends on the engine fuel grade 

Oxidation resistant

• Lube oil is always in contact with air and thus oxygen presence in oil is inevitable.
•  Oxygen causes sludge formation, acid production and bearing corrosion..

Load carrying capacity

• The load subjected to engine parts are high;
• Enough to withstand the pressure inside the engine.
• If not oil will be forced out and metal to metal contact result in wearing down of the machine.

Thermal conductivity

• engine are always in movement producing heat energy.
• This heat energy has to be carried away or else it might lead to wear down due to thermal stresses
• good thermal conductivity cool down the parts 

Detergency

• Additives are added which will prevent the buildup of small deposits in the metal surface. 
• in two stroke engine, the cylinder oil detergency is very important as it removes the deposits from the ring pack area and keeps the combustion space as clean as possible

Disperency

• Impurities to mix up with itself and keeps them suspended on the surface. 
• This makes it easy for the separator or clarifier to remove it from the oil.

High Flash Point

• The flash point should always be on the higher side so that in case of increase in temperature of the oil, fire hazard can be avoided. 
• Normally for marine engine lube oils, the flash point is always higher than 220̊ C.

Low Demulsification Number

The low demulsification number of the oil helps in easy separation of water from the oil 

What are the difference in Cylinder oil and System oil?

• Cylinder oil is detergent oil, with higher alkalinity.
• System oil is straight mineral oil

 Air–compressor oil is usually a synthetic oil that does not contain detergents commonly found in motor oil. A

Air–compressor oil is manufactured specifically for use in lubricating the ball bearings inside aircompressor