In the last decade, the automotive lubricant industry has seen high-mileage motor oils emerge and gain popularity for vehicles with more than 75,000 miles (120,000 km) on the odometer. These motor oils are advertised to combat the challenges that high-mileage engines face. But do they really work?

The truth is, high-mileage engines do have unique needs and could benefit from a motor oil designed specifically to address those challenges.

AMSOIL Tech Tips on Motorhead Garage with host John Gardner and AMSOIL product expert Len Groom: Is a High-Mileage Motor Oil Right for You?

Video transcript: Is a High-Mileage Motor Oil Right for You?

Featuring John Gardner, host of Motorhead Garage, and Leonard “Len” Groom, AMSOIL Director of Product Marketing (author profile).

John Gardner: Something you never wanna see. A connecting rod snapped in half and actually twisted a bit. Take a look at this. These bearings, well, this one’s brand new.

This one, totally worn out. And this piston, man, the top’s burnt. It’s beat to pieces. It looks terrible.

Welcome to this AMSOIL Tech Tip. You know, it’s all about the maintenance, my friends. Take a look at this graphic right here. This is a maintenance schedule, and those check marks, well, it’s riddled all the way across.

And, Len, it doesn’t stop at a 100,000 miles. It just keeps going and going and going. So you’re gonna have to have a specifically designed oil for that when you get up to that high mileage, don’t you?

Len Groom: Yeah. Exactly. And we do have a high mileage oil.

John Gardner: And you do. And pretty cool because it does a bunch of things. What about reduces oil consumption?

How does it do that?

Len Groom: Well, if you get an engine that have has a few miles on it, sometimes there’s deposits in there. So, we put a good heavy dose of detergency in there. Helps clean out the deposits, helps those rings reseal.

John Gardner: And, it also fights those deposits. I mean, the oil is formulated to do that?

Len Groom: Yeah. Correct. Because again, you don’t know the condition that the engine is in. It could have been, you know, not well maintained or things like that. So, you get in there with a lot of detergency to get it cleaned up right away.

John Gardner: The bottle says it protects against leaks. How does it do that?

Len Groom: Correct. You know you know, being a mechanic, they tend to leak after a while. Seals get hard, they crack. We’ve got a seal conditioning agent built into this product. It’s got a boosted level of that that helps soften those older seals and gives them a new life.

John Gardner: So how do I even find this oil and when would I know to switch?

Len Groom: Oh, 75,000 miles, 100,000 miles. You start getting in there. It’s really up to you. That’s kind of what we recommend. You can check out amsoil.com, type in your vehicle and make your selection.

John Gardner: Now, do you have a specially designed oil for a hot rod like the Crusher ’67 Camaro* here behind us?

Len Groom: We do. That would be our Z-ROD product on that car actually, because it is a classic and it is designed for that motor.

John Gardner: Well, whether you have a grocery getter, a hot rod like this, or a fleet vehicle, just go to amsoil.com. They have all the products you could ever need.

Here are a few of the most common challenges facing high-mileage engines and engines with an unknown maintenance history:

Increased oil consumption
Oil consumption is common among high-mileage engines. Over time, they experience increased wear, leading to greater oil consumption.

Using a suitable high-mileage motor oil that is thermally stable and resists volatility can help prevent oil consumption from occurring.
Seal leakage
High-mileage engines with aging seals are more prone to oil leaks. An aging seal loses flexibility, hardens and no longer effectively serves its purpose.

A well-designed high-mileage motor oil provides a boosted dose of seal conditioners to restore and recondition aging seals and help stop leaks.
Sludge and deposits
Over time, engines experience increased sludge and deposit buildup. This can be due to oil breakdown from high heat, low-quality oil, excessive idling or insufficient combustion of fuel.

A quality high-mileage motor oil can provide enhanced detergency, removing deposit buildup to help restore peak performance.
Compression loss
Engines can lose compression as cylinders and piston rings wear, eventually leading to reduced horsepower and increased blow-by.

A proper fluid film helps counteract compression loss by sealing combustion chambers to maintain performance. A purpose-built high-mileage motor oil is formulated to maintain viscosity and provide proper film thickness in extreme operating conditions.

High-mileage vehicles can still provide reliable performance.

The above challenges really do hinder vehicle performance. To protect your engine’s performance and help extend its longevity, it’s important to take steps that help counteract those issues. Our testing suggests that some companies are changing their labels to appeal to customers with high-mileage vehicles but not changing the oil inside the bottle.

Purpose-Built Protection

AMSOIL 100% Synthetic High-Mileage Motor Oil is specifically designed for the unique demands of high-mileage engines, helping extend the life of your vehicle. It delivers purpose-built protection at a time in your vehicle’s life where it could benefit from more-robust maintenance – including boosted detergency and an additive package that fights oil breakdown and leaks.

This may sound too good to be true, so to prove it, we subjected it to independent testing. The result: AMSOIL 100% Synthetic High-Mileage Motor Oil reduced sludge by 67%,* demonstrating its cleaning power that helps engines last longer and perform better.