Understanding Your Engine Oil

Posted on: 3 June 2019

Proper lubrication is key to keeping any engine running properly. Without it, friction builds up and creates heat that can damage or even completely destroy the internal parts of your motor. You know that maintaining proper lubrication in your engine means changing your oil on a regular schedule, but do you know the details of how oil keeps your engine running smoothly? And, perhaps more importantly, do you understand the details of the oils that you are putting into your car? This article will provide you with a quick primer on how oil works and what those viscosity numbers actually mean so that you can make an informed decision at your next oil change.

What Your Engine Oil Actually Does

It lubricates, right? This is certainly its key function. Your engine's internal parts are under tremendous pressure, are exposed to incredible amounts of heat, and are often moving thousands of times per second. All of this adds up to an incredibly extreme environment. Without oil, the friction inside of your engine would quickly cause irreparable damage. Even if the engine managed to run for a few minutes with no oil at all, it's likely that the worst damage would be done almost immediately.

Oil does more than just lubricate, however. Almost all modern engines are liquid cooled, but oil still serves a vital function in transporting heat away from the engine's combustion chamber. Additionally, the presence of oil prevents corrosion inside the engine and even serves as a cleaner. As your oil circulates, it picks up small bits of debris and prevents them from becoming lodged within the engine. This debris then ideally ends up in your oil filter, where it is flushed away on your next oil change.

The Dangers of Dirty Oil

Every role that your engine oil plays is compromised as the oil becomes dirtier. Dirty oil is a poor lubricant, it transfers heat less effectively, and oil that is saturated with debris is more likely to deposit that debris within the engine. Most people change their oil long before any of these problems become serious issues, but pushing oil changes for too long can easily result in serious engine damage.

Even worse, these problems tend to create positive feedback loops. As your oil becomes less effective as a lubricant, additional friction leads to more heat and the creation of more metallic debris. This, in turn, leads to the oil becoming even more polluted, ultimately creating more friction and more problems.

Choosing the Right Oil

It should be clear that clean oil is vital to engine longevity, but which oil should you choose? When browsing the oil shelf in a store, the numbers that are more important are the oil weights, or viscosities. These are generally given as two numbers, such as 5W30 or 0W30. The higher the number, the thicker the oil. In general, thicker oils are better at coating internal components and protecting the engine over the long term while thinner oils flow more easily and lubricate better.

Why are there two numbers? The "W" stands for winter, and the first number indicates the thickness of the oil when cold. This means that you can effectively choose an oil that will be thinner on cold starts, providing better lubrication while the engine is cold, and thicken as temperatures increases to provide better protection.

Your vehicle's manual should recommend a range of safe oils to use, and you should follow these guidelines. When selecting from within that range, keep your climate in mind. If you live in a very cold climate, thinner oils will work better. For very warm climates, favor thicker oils. Regardless of which type of oil you end up picking, always be sure to change your oil regularly and according to your manufacturer's recommendations.

If you need help selecting or changing your oil, contact a local auto shop like Furgerson's Garage