High-mileage oil may extend the life of an older car, but it carries a high price

Karen Ballard/Netflix

If you own an older car with six-digit mileage or close to it, you may wonder: Is high-mileage oil worth the cost?

At a cost of $2 more per quart than regular oil, it’s a question worth researching with auto experts and your mechanic.

What is high-mileage oil?

High-mileage oil is oil designed for use in engines with more than 75,000 miles of use. It contain additives that revitalize seals, clean out the engine, reduce wear and tear on the engine, and help it run smoother.

According to manufacturers, this oil improves fuel efficiency and enhances performance. Ideally, this specialty oil extends the life of a vehicle by reducing problems and making car maintenance easier.

How does high mileage oil work?

Engine oil has several key purposes. It lubricates the parts of the engine so they operate smoothly and withstand the stress of working under conditions of extreme heat and pressure.

Oil also traps debris so it does not enter the engine and subsequently clog parts.

As for high-mileage oil, it adds additional layers of protection. It has greater viscosity than regular engine oil, making it better at preventing metal-to-metal contact that leads to faster wear.

Additives and detergents

High-mileage oil contains ingredients designed to address problems common in older engines.

For example, the additives used in high-mileage oil help engine seals. Over time, these plastic pieces become brittle and crack, which leads to oil leaks. Sealing conditioners inside the oil help restore these seals pieces to their original size and shape.

Detergents and cleaners in the oil also help to remove sludge that builds up inside the engine, causing it to run smoother, making it easier to check for leaks and reducing the amount of wear on your car’s hoses and other parts under the hood.

Making the switch to high-mileage oil

Although oil manufacturers recommend switching to high-mileage oil at specific mileage points, it may not be necessary for some makes and models, or until the engine starts showing signs of wear.

To some mechanics, the extra cost of the oil isn’t worth the price, if the engine still runs well. They suggest using regular oil as long as possible and switching when the vehicle starts doing the following:

  • Consuming more oil between oil changes.
  • Starting slowly in the winter and running hot in the summer.
  • A slower throttle response.
  • A drop in gas mileage.
  • Leaving oil stains on the driveway from leaks from the engine.
  • Spewing blue or white smoke from the exhaust produced by oil burning on the hot engine surface.


High-mileage oil, with seal conditioners and cleaners, is useful in some older vehicles. For some people, the extra cost at each oil change is worth the extended life of the car.

Others may notice no difference in performance, especially if the car runs well. Check with a mechanic before deciding if high-mileage oil might help your car’s performance.