What Happens if You Do Not Change Your Oil?

Oil is arguably the most important fluid your car needs, besides fuel, and its upkeep is essential to the vitality of your vehicle. Oil lubricates, cleans, and keeps the car engine from overheating. Yet, many drivers push their oil well past recommended limits or skip oil changes altogether. They don't realize the risks these actions pose to their vehicles. Using the same oil once or twice won't have a significant effect on your car. However, the longer you go without changing your oil, the more issues your car will have.

1. Your Engine Will Seize

The primary function of car oil is to lubricate the cylinders, pistons, and various other components that make up your car's engine. Without it, metal-on-metal friction can generate enough heat to effectively weld surfaces together and cause the engine to seize. If this happens, the damage will be extensive, and you'll need to replace the engine. Engine replacements can cost thousands of dollars. Often, drivers are better off selling their engine for scrap and purchasing another vehicle.

The way to avoid these issues is simple: Change your oil regularly. Oil is essentially the lifeblood of your vehicle, and changing it is one of the easiest, most inexpensive car maintenance routines you can perform by yourself. The process takes less than ten minutes, and your car will run better if it's done regularly.

Most mechanics recommend changing the oil every 3,000 miles or every three months. For modern cars that use synthetic oils, you probably won't need an oil change until around 5,000 miles. However, pushing your engine past that point can be fatally dangerous.

2. Your Engine Will Overheat

In some cars, the internal combustion engine also utilizes oil for a process called oil cooling. As the name suggests, oil cooling is the use of engine oil as a coolant. Car engines produce a lot of heat, which they transfer to the oil. Oil is then passed through a type of radiator called the oil cooler, which sends cooled oil back to the hot engine for continuous cooling.

This cooling system prevents the engine from overheating. Nevertheless, oil (and any anti-wear components present in the oil) breaks down at high temperatures. Its chemical make-up becomes unstable, and it doesn't absorb heat as readily. If you don't change the oil consistently, you increase your engine's chance of overheating.

3. Your Engine Will Become Less Efficient

The oil in your car also cleans the engine and prevents corrosion. As oil travels through the various components of your engine, detergents present in the liquid collect debris and other insoluble by-products. These detergents carry various contaminants to the oil filter, where they are summarily removed.

However, the longer oil circulates in your engine, the more debris and iron deposits it accumulates. If left unchanged, the thick liquid will gain a sludge-like consistency, making it difficult for oil to move between the inner parts of the engine, much less lubricate those mechanisms.

Furthermore, heat from the engine will deteriorate detergent additives and minimize the oil's cleaning properties. Continuous exposure to high temperatures increases the rate of oxidation in oil, which, in turn, promotes varnish and engine wear. You don't need to change your oil right at 3,000 or 5,000 miles, but the longer you leave old oil in your engine, the poorer your engine's performance will be.

4. Your Car's Health Will Decline

For a better understanding of how not changing your oil can harm your car, consider the results of a diagnostics test performed on a 2007 Dodge Caliber in early 2016. Blackstone Laboratories evaluated the oil of a nine-year-old vehicle, which made strange noises and had poor engine performance. Lab results revealed high levels of iron, likely from worn steel parts of the camshaft or cylinder liners. The amount of iron found in the vehicle's oil was more than 15 times that of the universal average.

According to the lab, these issues developed because of the vehicle's poor oil quality. Apparently, the car's age had little to no effect on its health. The owner of the car hadn't changed the oil in more than 12,000 miles. Thus, it began to show signs of engine wear like that of much older models. It's likely that the engine would have shut down if the owner continued to push it in that condition.

Car engines are sturdy, durable, and built to withstand constant use. If given proper care and consideration, your engine can last for over a decade. However, it can't handle exposure to unchanged oil for extended periods of time. Therefore, if you've used the same oil well past recommended mileage limits, do yourself and your car a favor by not skipping your next oil change.