Why Diesel Engine Oil Changes are Key for Your VGT Turbo

Contrary to what you may have heard, changing your oil regularly can help extend the life of your engine and save you money. It's actually one of the cheapest routine maintenance actions you can perform on your diesel truck. 

This might contradict what you've heard from different sales people. A lot of times, when people are looking to buy a truck, they're mostly concerned with the fuel economy and the maintenance costs of the vehicle. In other words, what the lifetime expenses of the truck are going to be. So, if the manufacturer or sales person can stretch out that oil change interval, it seems to reduce that lifetime cost. 

We would challenge that, though, because regular oil changes are actually one of the least expensive things you can do to keep your engine running for miles and miles. We'll take you through why!

You can also check out our video on the topic:



Has stretching your oil change intervals caused damage to your diesel engine? Our ASE Certified Technicians can help you get the right parts to get your engine running great!

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How Diesel Oil Changes Should Be Figured


oil change intervals oil lubrication | Highway & Heavy Parts


Figuring oil change intervals can actually be a little complicated. If you look at cars, they now give you a light to know when to change your oil. This is because it's no longer driven off of miles traveled, but based on how many gallons of fuel you've consumed. This came about because the duty cycle of the engines is completely different.

Let's say you've got a truck that's running down the road that may be a line haul truck travelling 350 miles, and it gets on the expressway, sets the cruise control and doesn't get off until its destination. Depending on what weight he's carrying, whether he's in hills, whether he'd loaded or unloaded, those miles are not equal miles. So, if you were to change oil based on that alone, it's really hard to factor it properly.

Now, if you take the garbage truck that goes through your neighborhood, that accelerates roughly 150 feet before it runs the hydraulics, dumps the garbage, and then hits the throttle before coming to the next can—over and over again throughout the day. And that truck might only travel 70 miles each day.

So, if we were to change oil at 10,000 miles, the garbage truck that's working harder than the truck with no load, those miles are not equal miles. Oil changes should instead be tracked by how much fuel goes through the engine.

Another time you need to pay attention to your oil change intervals is after breaking in your diesel engine. Learn more in our post about oil change intervals after engine break-in.


Why Regular Oil Changes are More Important Now Than Ever

In the past, operators would push their oil change intervals into the neighborhood of 20,000-30,000 miles, using synthetic oils. With those engines, synthetic oils would allow you to extend past the time you would normally need to service the truck without causing much harm to your engine. 

This is no longer the case.


EGR Systems.

Because of these EGR systems, we're putting a higher concentration of contaminants into the oil. Today, we're asking a lot more from our oil than we did in the past. As more particulates are produced and find their way into the oil, the more often it must be changed.


Symptoms Your Diesel Engine Needs an Oil Change


diesel engine oil change symptoms | Highway & Heavy Parts


Pay close attention to these symptoms to see if your oil is need of a change.

Dirty oil can have lasting effects on your engine if it's not changed at the proper intervals. Operators that stretch intervals run the risk of getting their new oil dirty much faster than normal. Maintaining your oil on a regular basis will help keep the oil's detergent  properties and will carry out any absorbed debris when changed. When oil is stretched, the detergent properties are weakened and will leave contaminants behind when drained. 

Oil dependent components suffer greatly when it's not lubed properly with dirty or low oil. Bearings, camshafts, rocker levers, and similar components will all wear prematurely, causing additional problems inside your engine. It's likely something you won't see the first time you miss the interval, but if you continue to stretch, all those small clearance areas that have an oil film in them will start to show wear faster. These happen over time, yet cause serious failures when the damage has run its course.

For example, within the turbocharger, you have a turbo shaft that's supported on bearings, and that oil film is crucial in making that turbo work. So if we have debris going through the oil, or the oil has thinned out and lost its lubrication properties, the shaft isn't cooled properly or supported properly, and we start to see issues within turbochargers.

Overheating and oil consumption are related symptoms. Burning oil during extended periods can lower the level of oil in the oil pan. The oil pan also acts like a cooling tank, cycling cooled oil back into the engine. The loss of oil lowers the engine's cooling capacity, causing overheating. 

Is your engine running through oil? Find out what can cause excessive oil consumption!


How are These Problems Related to My VGT?

So, how exactly can this harm my VGT turbocharger? 

Well, the VGT is one of the last places to get oil. The turbo shaft sits inside of the housing on bearings that are lubed by the engine oil. It depends on that oil to keep the turbochargers spinning and performing up to spec. If contaminated oil finds its way into the VGT, it can damage the shaft or bearings. 

If little to no oil gets to the VGT, you run the risk of expanding clearances inside the housing and seizing the shaft. This will lead to a failed VGT turbo.

Read our post on turbo failure from contaminated oil to learn more!


So, how can we avoid issues with our engine oil?  Change your engine’s oil every 3,000 miles when using a standard oil and 5,000 to 6,000 miles using a synthetic oil.

Use CJ-4(low ash) engine oil, if recommended by the manufacturer.  At fill-ups, use Ultra-Low Sulfur Diesel Fuel.  During oil changes, collect a sample of your used engine oil for analysis to see if there are any contaminants in your storage system.  Remember that usually you get what you pay for when it comes to the oil you put in your engine. 


Still want to know more about oil change intervals, or need replacement diesel engine parts? Our ASE Certified Technicians can help you out! Call them at 844-304-7688, or request a quote online!