The Importance of Choosing the Correct Engine Oil

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Guest Article by Don Elfrink*

Engine oil comes in a bewildering array of weights, brands and types. A quick glance at the shelves in your local auto parts store will show you everything from 5W30 to full synthetic formulations to 20W50 and more. Which is the right oil for your car? It can be tempting to buy oil based on the recommendation of friends or family, or even to use whatever weight you’ve been using for years in your previous cars. However, this is the wrong approach to take. It’s important that you choose the right oil for your vehicle.

The Problem

The problem here is that your engine is designed to work with a specific weight oil. For instance, many newer engines are designed to run 5W20 or 5W30 – this is a lighter weight, thinner oil. Using something heavier than this can cause problems. If you have been mentally conditioned by years of using heavier oil in an older car because of leaks or “just because”, this can be a hard habit to break.

Understanding Oil Weight

Part of the issue in choosing the correct oil is understanding what all those weight ratings really mean. For those who have no real experience in the automotive industry, it can seem like a string of meaningless letters and numbers. It’s not that difficult to understand, though. The key is to realize that today’s oil formulations have a dualistic nature. They’re designed to operate differently in different temperatures. Older oil formulations are denoted by “SAE” and are often referred to as “straight weight”. That means they operate like a single weight oil, regardless of what the temperature is.

Today’s oils are made to work differently in winter and summer driving. That’s what the W stands for in the oil weight – winter. So, an oil with a weight of 10W30 would operate like 10-weight oil during the winter and 30-weight oil during the summer. That’s important to understand, because you need thinner oil during cold periods and thicker oil during the heat of summer. In the past, you actually had to change oil weights seasonally. That’s no longer the case.

How to Tell Your Type

When it comes to choosing the type of oil you use in your car, your choice shouldn’t be random. The best option is to use what the manufacturer recommends. Most modern vehicles have this shown on the oil filler cap. If it’s not there, you might check the owner’s manual. Failing that, you can contact a dealer that specializes in your brand and find out what they recommend for your make and model. If you have an older car, or the oil filler cap has been replaced, you should contact a dealer and find out what the automaker recommends for your engine.

The Problems of Using the Wrong Oil

Keeping your engine oil clean and changed regularly is important, but it’s just as important that you have the right oil in the engine. Many different problems can develop from using the incorrect oil for the application. For instance, if your car is rated for a 5W20 blend and you choose to use 10W30, you’re putting much thicker oil in the engine than it was designed to use. The first thing that will happen is you’ll see more sluggish engine performance. You’ll also noticed decreased fuel economy. If there’s a significant disparity between what you’re using and what the engine was designed to use, you might even find that the oil doesn’t lubricate quite as well.

Always use the oil that your engine was designed for. If you’re going with a thicker oil because of leaks, it’s better to repair them and replace leaking gaskets than run oil that is too heavy for your car.

* About the author: Don Elfrink is the owner of AutoMatStore. AutoMatStore specializes in selling custom floor mats for all weather and all vehicles. He has previously written guest articles for our website, which you can find at:

1. Keep Your Car Looking Great by Detailing It

2. 7 Useful Tips to Prepare Your Car for Cooler Weather

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