High-Mileage vs. Synthetic Oil: Key Differences

Synthetic vs High Mileage Oil

Synthetic oil is a type of lubricant that's made from chemical compounds. These compounds then break down and rebuild the petroleum molecules.

Under the microscope, a drop of synthetic oil shows that millions of molecules are almost the same size. Conventional or mineral oil, on the other hand, is made from refined crude oil.

A drop of conventional oil under a microscope shows millions of different structures and shapes of petroleum molecules.

Vehicles commonly use high-mileage oil to address various problems they encounter, such as smoke emissions, oil consumption, and engine wear. It can also help prevent oil seepage and leaks.

Let’s discuss the major differences between high-mileage oil vs. synthetic oil as well as other critical things you need to know about these types of motor oil.

Is Synthetic Oil Better Than High-Mileage Oil?

Despite the various advantages of synthetic motor oil, some people still wonder why it's more expensive than regular oil. This is because of the innovation and science involved in making this type of oil.

Almost 80% of motor oil formulation comprises base oil while the remaining 20% comprises additives.

Compared to conventional oil, synthetic base oil molecules have uniform properties and are more likely to have a high purity level. This has led to a shift in the automotive industry toward cleaner and higher-quality products.

Due to the use of natural gas as the base oil, synthetic motor oil delivers even better performance than regular oil.

It can also help protect your vehicle's engine from threats like wear and corrosion. With the help of this technology, your car can experience the best possible fuel economy and performance.

Is High-Mileage Oil Same as Synthetic Blend?

High-mileage oil is created using a combination of natural and synthetic oils. On the other hand, full synthetic oil uses a robust synthetic base.

These two oils have similar additives to address the various problems that can arise from wear.

Does High-Mileage Oil Make a Difference?

High-mileage oil can help address specific problems your vehicle's engine is experiencing due to age. It can also help prevent engine wear and improve its performance.

These are some of the differences it makes:

1. Reduced Oil Consumption

Older vehicles tend to leak and burn more oil due to the degradation of their engine seals. High-mileage oil can help reinvigorate these seals, which results in less consumption and less burnoff.

2. Protection from Damage

Older vehicles are prone to experiencing more general wear and tear than their younger counterparts. High-mileage oil can also help protect the entire engine by adding additional additives.

3. Less Sludge

Older engines tend to have more sludge deposits than their newer counterparts due to using other motor oils. High-mileage oil can break down these deposits and remove them.

High-Mileage Oil vs. Synthetic Oil

High-mileage oils and synthetic blends are two different oils. Synthetic oils are a combination of full synthetics with conventional oils. In contrast, high-mileage oils combine synthetic oils with petroleum-based oil and other additives.

The main advantage of high-mileage oils is that they can contain various additives that can help reduce the wear and tear on your vehicle's engine.

They also supposedly have conditioners that can help seal leaks in older vehicles. On the other hand, synthetic blends aren't advertised to contain these same additives.

Although synthetic blends aren't advertised to have the same additives as high-mileage oils, they can offer additional protection for older engines.

High-mileage oils are typically more expensive than synthetic blends. However, this shouldn't be a cause for concern as your car's engine needs free-flowing oil regardless of the type.

Even if your car's odometer reads less than 50k miles or your vehicle's mileage exceeds a hundred thousand miles, synthetic and high-mileage oils can still be used on your engine. The additives in both types of fats are generally safe for most engines.

What Are the Advantages of Synthetic Oil?

In addition to being safer, synthetics offer various advantages over conventional engine oils. The list below shows the top advantages of synthetics over their traditional counterparts. It assumes that the additive package is the same between the two types.

The difference between synthetic and high-mileage oils is the package's additive package. Since most synthetic formulations have a superior additive package, it's challenging to determine which one is the better performer.

When it comes to chemical degradation, conventional mineral oils are typically more prone to experiencing issues than synthetics.

These include exposure to harmful conditions such as water contamination, combustion byproducts, and pro-oxidation. In addition, other factors, such as extreme heat and metal particles, can also affect the oil's performance.

With a higher viscosity index, synthetics are more stable when compared to mineral oils. Their properties will react less to temperature changes during operation and startup.

One of the essential properties of synthetics is their ability to produce a film thickness designed to protect your car's metal surfaces from excessive wear and friction.

If your car's engine gets exposed to shallow temperatures, mineral oils might develop a thick and potentially unusable oil that can't circulate properly within the system. This could cause engine failure and other issues.

Compared to other oils, synthetics are generally less volatile. This means they can prevent the oil from leaking into the engine's exhaust stream, contributing to atmospheric pollution.

One of the main reasons why people prefer synthetic oil is its long life. According to some companies, it should be changed to around 5,000 to 7,000 miles annually.

This is significantly longer than the manufacturer's suggested change interval. However, if you use a high-mileage oil, it's still recommended to change it regularly.

Disadvantages of Synthetic Oil

One of the most significant disadvantages of synthetic oil is its high cost. It's typically around two to four times more expensive than conventional oil.

Another disadvantage of synthetic oil is that it's potentially more prone to experiencing precipitation-related additives. These can potentially lead to separating the various components from the oil.

Compared to mineral oils, synthetics may offer a slightly lower fuel economy for highway driving.

This is because synthetics require more additives to improve their viscosity index. This is because mineral oils typically need more additives to reduce viscosity friction.

When To Use High-Mileage Oil?

High-mileage oils contain additives that can help reduce the number of oil leaks. It's also possible that the oil could stop leaking after a couple of oil changes. This could help prevent oil spots in your driveway.

High-mileage oils also contain additives that can cause seals to swell and cause o-rings to develop. This could result in lower oil consumption.

In addition, some vehicles' older valve-guide seals may have reduced seepage, resulting in lower oil consumption.

Although high-mileage oils are made for vehicles with 75,000 miles or more, educating yourself about their use is still essential.

For example, if you're experiencing issues such as loss of power or strange noises, it's possible that your vehicle's mechanical system is not working correctly.

If you have a high-mileage vehicle that's been well-maintained and is trying to minimize the effects of engine wear, high-mileage oil might be the best choice.

However, it's essential to remember that high-mileage oil won't cure all of your vehicle's mechanical issues.

Should High-Mileage Oil Be Used in New Vehicles

The goal of a joint effort by car manufacturers was to create a global standard for the use of engine oils. The action was supported by the American and Japanese auto industry groups. Some companies participating in the project included General Motors, Ford, and DaimlerChrysler.

Car manufacturers can now quickly identify the type of oil used in their vehicles through the licensing and certification system created by the ILSAC.

By looking at the API service symbol or the starburst symbol on a motor oil bottle, you can tell that the product has been thoroughly tested and approved by the manufacturer.

Due to the introduction of new technologies and the need for more fuel-efficient cars, the classifications of engine oils have to change. This is why reading the labels of the products you buy is essential.

The API now has a service classification standard for gasoline engines known as SN or SN Plus. For four-stroke vehicles that use diesel engine oil, the current category is CK-4.

If you have a 2017 or later low-sulfur diesel engine, you might need an FA-4 oil because these are the oils explicitly designed to reduce greenhouse gas emissions.

Since the new classification of motor oils has been compatible with the latest technologies, it shouldn't cause any issues when using a unique type of oil for your vehicle.

However, it's important to note that older service category oils can still cause problems for newer cars.

Follow the manufacturer's recommended oil changes for your vehicle. Using high-mileage oils in a new car would be very ill-advised.

Since no manufacturer recommends using this type of oil, it's essential to follow the manufacturer's manual.

Although it's unlikely that high-mileage oils would harm your new car's engine, it's still essential to follow the manufacturer's instructions.