Oil Change – More than you wanted to know

Oil Change – More than you wanted to know

Engine Oil

Most cars on the road today use multi-grade oil — one that can work efficiently in cold and hot weather. A multi-grade oil is rated by two numbers, such as 5W-30.


The oil and the oil filter need to be periodically replaced; the process is called an oil change. While there is an entire industry surrounding regular oil changes and maintenance, an oil change is a relatively simple car maintenance operation that many car owners can do themselves. It involves draining the oil from the engine into a drip pan, replacing the filter, and adding fresh oil.

About the oil classification system

Each engine oil comes with a classification indicating its viscosity, which is its friction or resistance to flow. In a multi-grade oil, the first number indicates how the oil will flow when it is cold. The lower the number, the lighter the oil and the better it will perform at lower temperatures. The second number indicates the thickness of that same oil at high temperatures. For example, a 5W-30 oil will flow as a 5-weight oil at zero degrees Fahrenheit and as a 30-weight oil at 210 degrees Fahrenheit

Why viscosity is a concern

During cold starting, only a small amount of oil is present in the upper parts of engines. To lessen the friction when upper engine parts, such as the valve train, pistons, overhead cam and cam bearings, scrub against each other, a lower viscosity allows the oil to reach the components more quickly.

Why 5W-30 and 5w-20 oils are so popular

Many vehicles today leave the factory with 5W-30 or 5w-20 engine oil. Vehicle manufacturers recommend them because they are lighter oils that perform well in a range of temperatures and help improve gas mileage.

Synthetic Oils

Not all motor engine oils are 100% petroleum. Synthetic oils, which are primarily chemically compounded lubricants, are also available. They can provide:

Higher viscosity stability over a wider temperature range
Reduced oil thickening
Reduced wear and increased load-carrying ability.

Which oil is right for your car?

The simplest and safest way to find out is to check your owner’s manual…or talk to your Midas mechanic.

Oil Filters

Oil filters are designed to trap foreign particles suspended in the oil and prevent them from getting to the engine bearings and other parts.


Early automobile engines did not have oil filters, having only a rudimentary mesh sieve placed at the oil pump intake. Consequently, along with the generally low quality of oil available, very frequent oil changes were required.

So always follow the manufacturer-recommended service schedule