Oil Viscosity Chart

What is multiple viscosity motor oil

Take the example of SAE 5W 30 motor oil .It is a multi viscosity oil.It acts as SAE 5 when you are starting your engine and as SAE 30 when the car is heated.The engine needs to be thin when you start the car and thick when it is heated.

In multi viscosity oils,The viscosity do not vary much with the temprature.It has more additives than the single viscosity motor oils.These additives are responsible for keeping viscosity in check with respect to temprature changes.

• SAE 10 w 30 : 90 percent base oil 10 percent additive
• SAE 10 W 40 : 80 percent base oil 20 percent additive
• SAE 30 : 95 percent base oil 5 percent additive(single viscosity oil)

Oil clearence area is located between bearing and shaft.You want your oil to be thin at the starting time so that it flows to clearence area.You want it to be thick when engine is heated so that it does not overflows from oil clearence.

Energy conserving oil

These reduces your oil consumption and increase mileage of your car by reducing friction between components.

Note : Check before buying SAE 10W 40 motor oil as some car manufacturers do not recommend its use.

Synthetic oil

These oils are prepared from chemicals(non petroleum products).They gain popularity in 1990's.

Pros

Gives better mileage.

Low viscosity changes across tempratures.

Cons

High cost

Not recommended for new engines.