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Buying Guide - What's the Right Oil For My Car?

Snapshot: Have you ever wondered what all those numbers written on the can indicate? There are different kinds of ratings for engine oils like 20W40. We discuss here what these numbers signify and what the different types of engine oils are.

Every time you take your car for service, they pour in a large can of engine oil into your car engine. Have you ever wondered what all those numbers written on the can indicate? There are different kinds of ratings for engine oils like 20W40. We discuss here what these numbers signify and what the different types of engine oils are.

What is this 15W50?


The numbers on both sides of the W signify viscosity rating of lubricating oil. Any oil with W in its rating has been tested in cold temperatures as well. The number after the W indicates the viscosity of the lubricating oil at operating temperature of engine which is around 100 degree Celsius. In case of engine oil rated 15W50, the viscosity at high temperature would be equal to SAE50 engine oil in this case. The 15W indicates the cold viscosity of this engine oil. While this 15W won’t make a difference in the performance of vehicle, it would help during cold starts. A low cold viscosity would allow the oil to flow quickly in the system and thus engine won’t run dry for long.

Mineral? Semi Synthetic? Synthetic? You must have heard these termed mentioned along with the grade of engine oils. Many manufacturers recommend you to switch to synthetic oil even though they keep the relatively cheaper mineral oil option open for you.

Mineral Oils


Mineral oils are a product of refining process and thus contain paraffin. These oils serve well for most people. They are relatively cheaper than the semi synthetic or synthetic engine oils making them more cost efficient. These engine oils are better suited for use during running in period as the wear and tear is essential for a new engine and the high lubricating property of synthetic oil hinder the process. With mineral engine oil, the oil change intervals are frequent as it tends to deteriorate early. The performance isn’t very impressive either. These oils are good for engines running at slower speeds as they don’t fare up very well. They are relatively unstable and tend to lose their properties in extreme conditions. At high engine speeds or very high temperatures, the oiliness goes down which increases the wear in engines. Also they tend to separate out in layers if left in the engine for long time. So if you don’t follow the change intervals properly, you might end up with ruined engine oil which is something really dangerous. 

Synthetic Oils


Synthetic oils are chemically synthesised from molecules of same size and generally offer better lubrication.While most manufacturers recommend synthetic engine oils, there are some who keep quiet about it. So before you switch to a new oil, check your vehicle manual or consult the authorised service center. The synthetic engine oils are usually made from Group IV based oils though now there are petroleum derived synthetics as well that are the Group III based oils. You might find oils of same grade priced differently because they belong to different groups. Obviously we would suggest going for Group IV oils. Synthetic oils tend to last longer than the usual mineral oils. This is because they are chemically fortified to withstand the extreme conditions inside the engine. This way you get excellent lubrication even when most other oils break down in extreme heat. The flow is also good during the winters and very high engine speeds. The sludge formation that we mentioned in case of mineral oils is very low in case of synthetic oils. While it appears all good about synthetic oils, they have some drawbacks as well. Obviously one of them is high cost of these oils. Then they don’t perform really well in high mileage engines as they are known to cause oil leaks by affecting rubber seals.

Semi Synthetic Oils


As the name suggests, semi synthetic oils offer a compromise between these two types of engine oils. These oils contain a blend of the two different type of oils mentioned above. For common motorcycle engine oils, the cost of synthetic engine oil can be around four times that of mineral oil. Semi synthetic oils are available at relatively affordable prices and offer some of the advantages as full synthetic oil. Usually they contain up to 30 percent of synthetic engine oils. While the drawbacks of mineral oil aren’t eliminated completely, the performance is improved significantly. The engine runs smoother and can run at higher speeds without any trouble. Sludge formation is also reduced as compared to mineral engine oils. The engine oil replacement intervals also sit between the two other types of engine oils. These engines are a good upgrade from mineral oils if you are not willing to spend the amount for synthetic oils. Moreover in smaller engines, the advantage of using synthetic engine oil isn’t very significant. In this case, people can use semi synthetic engine oils for minor performance and efficiency boost without shelling out a lot of money.


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