Turbocharged Engines Are Changing the Way We Think About Oil Changes

Turbocharged vehicles have officially flooded the automotive market as automakers strive to make good performance numbers while meeting green legislation obligations – and it’s changing the way we need to approach oil change maintenance.

Motor oil has long been known as the lubricating life blood of the internal combustion engine – Without it, metal on metal friction of the internal components would cause the engine to seize after a very short time. Modern engines are no different. In fact, modern engines feature additional components, such as turbochargers, which depend heavily on high quality, clean and durable motor oil for lubrication.

We’ve already covered one of the most common causes of turbocharger failure in the past and at that time, we made a point to discuss the massive number of turbocharged vehicles that are hitting the roads of North America lately. The numbers are simply staggering – By 2025 well over half of the vehicles on the road will feature a turbocharger paired with a small displacement engine. Ever tightening government regulation spurred by green legislation will ensure that these numbers continue to climb for as long as internal combustion engines exist. Turbochargers are here to stay in great numbers and that means we have to unlearn a lot of what we think we know about lubrication, filtration and oil change intervals.

Good Lubrication is Critical for Turbochargers

Most modern turbochargers employ a plain bearing system to control main shaft movement and oil is needed to lubricate these two components. The bearings rely on a film of motor oil under high-pressure to support the main shaft while ensuring that there is no contact between the shaft and the turbo housing. Essentially, the shaft is floating on the film of oil while it spins at about 240K RPM or 4k rotations/second. Even with the oil doing its job, the sheer speed of the rotations results in an incredible amount of heat build-up.

Lubrication Helps Heat Dissipation

Another function of the motor oil in the turbocharger is heat dissipation. If the temperature gets high enough, the heat could cause the metal components of the turbocharger to soften, resulting in catastrophic failure. When considering temperatures and speeds this extreme, oil starvation for even a few moments during high-speed or aggressive operation could lead to heat build-up that micro-welds the metal components of the turbo, which would cause the turbo to seize.

charred turbocharger burned by excessive heat

Heat dissipation fail? We’re not sure about the story behind this one, but this turbo experienced some extreme heat!

Common Causes of Turbocharger Failure

There are three well-known causes of turbocharger problems that typically lead to failure. The function of a turbocharger is to force the induction of air into the combustion chamber of the engine, so it makes sense that one of the common causes would be air filter neglect. In order for the turbo to do its job effectively, it has to be well lubricated ­and that’s possible because of the same oil flowing through the rest of the engine. Knowing that, it’s not hard to see why the other two common causes of failure have something to do with poor lubrication. With turbocharged vehicles, oil change maintenance is more critical than ever.

Problem 1: Oil Contamination

With our explanation of how motor oil lubricates the internal components of a turbo, it should come as no surprise that dirty oil is really bad for them. Turbocharger components are engineered to incredibly precise tolerances, usually to within 1 micron. And 1 micron is about 100X smaller than the width of a human hair. Turbochargers are manufactured to such a high degree of precision so they can maintain the high shaft speeds mentioned previously. Any change in these tolerances will spell big trouble for the turbo. Well, as motor oil is repeatedly cycled through the engine it gradually becomes contaminated. This happens because carbon created during the combustion process manifests itself as tiny particles in the motor oil. Eventually, high concentrations of these particles in the oil will act as an abrasive – eroding the surfaces of the bearings and impeller shaft and increasing the amount of clearance between them. This is precisely what you DON’T want to happen inside of a turbocharger.

oil contamination caused these main shaft striations
Visible striations on the turbocharger main shaft caused by metal to metal contact with the bearings.

Problem 2: Oil Starvation

Oil contamination can lead to the premature wearing of internal turbo components such as the bearings and main shaft, but it can also lead to simultaneous oil starvation which is an equally serious problem. Excessive carbon buildup in the oil wears down metal components and it can also lead to clogging of the oil feed holes as well as the supply and return pipes. Any occlusion of the feed holes or pipes will result in oil supply problems. Oil starvation in an engine is never a good thing because when the engine is starved for oil there are metal internal components touching one another, which results in friction and heat that will eventually lead to seizure. The same is true for the internal components of a turbocharger. One of the functions of motor oil in the turbo is help dissipate heat. Restriction in the oil supply will result in excessive heat and the eventual softening of metal components and, you guessed it – catastrophic failure.

oil starvation caused the catastrophic failure of this turbocharger
This compressor wheel began rubbing the inside of the turbocharger housing as a result of oil starvation.

Throw Conventional Oil Change Wisdom Out the Window

Thankfully oil contamination and oil starvation are really easy problems to mitigate in 2021. Effectively doing so requires us to change the way we approach oil change maintenance for turbocharged vehicles. For as long as anyone can remember, conventional wisdom has said that regular oil changes should be done about every 3,000 miles. As both engines and lubrication have evolved, that number has crept up into the 5,000, 7,500 and even 10,000+ miles range for many manufacturers. Unfortunately for drivers who like the prospect of paying for half as many oil changes, extended drain intervals are not a smart choice for a turbocharged vehicle.

The Solution: Synthetic Oil Paired with a High-Quality Oil Filter

The best way to mitigate the threat of turbocharger problems due to oil contamination or starvation is to shorten oil drain intervals while continuing to use high-quality synthetic lubricants and a high-quality synthetic oil filter. The use of synthetic lubricants goes a long way towards protecting the turbo because it doesn’t break down and lose viscosity nearly as quickly as conventional motor oil does during the combustion process. Less breakdown means less contamination and less contamination means less wear. Synthetic oil is also much better suited to stand up to the extreme temperatures generated by the turbocharger’s main shaft and is better when it comes to the critical task of dissipating heat. The use of synthetic oil is an important step in the right direction, but make sure to use a filter designed specifically for synthetic lubricants.

A high-quality synthetic oil filter usually utilizes a synthetic blend media which is more efficient – meaning it can filter smaller particles more effectively. Of course, this results in less turbo wear. The unique media of a synthetic oil filter also allows the filter to hold about twice as many contaminants as a conventional oil filter. Twice the dirt holding capacity is a really big deal when you consider how abrasive contaminants are for the surfaces of internal components of the turbocharger. With the right oil filter, drivers can rest assured knowing that all of the contamination in the oil is staying right where it should, in the filter and away from the turbocharger.