Diesel Engine Oil Change Intervals

Last updated: Jul 05, 2021 Johnathan Cokerhow tos

After working for many different companies on diesel engines I have got a good idea of the oil change intervals. This is essential in your maintenance routine. When should you change the oil in a diesel engine?

As a general rule, you should replace diesel engine oil and filter at 7500 miles, 6 months, or 400 work hours. Depending on the application of use and quality of the oil, you may increase the time between replacements.

Oil change

What if I use my diesel differently?

How you use your diesel can change how often it is best to do the lube and filter change. While I will not list specific mileage or hours you can figure out what works best for your application.

City Driving

Your engine oil will break down a bit faster if your diving solely in town. The constant acceleration and stopping can have a negative impact on all your components. It just naturally causes more wear. You might consider stating close to the recommended oil change intervals to wash out all the contaminates.

PTO Applications

Whether you are in farming or have a vacuum truck/dump truck, there are several applications that use a PTO and ramp up the RPMs to do work. This is where the 400 hours of work will come into play. This is really hard on the engine. Diesels were made for high idle but most likely you are up and down quite a bit. FOr the same reasons above you might consider stating close to the recommended oil change intervals to wash out all the contaminates.

Long Haul

When you wind out your diesel engine it loves to stretch its legs! As you run your engine for longer periods of time the oil if=s moving and shaking. You can leave it in for a long amount of miles or hours. You can sneak some extra miles on the engine with this application. Of course based on your discretion. I know at one trucking company I worked for they let the long haul trucks go 15,000 miles between changes. As always investigate and make an educated decision because its your money on the line.

Aren’t diesels meant to “Run dirty” Why do you need to change it so much?

Modern diesels need the oil changed! They have progressed to such small orifices and everything is so tight and measured down any foreign particles with likely cause damage.

Diesel engines make a ton of soot and little particulates. As the piston combustion happens left overs get into the engine oil. leaving contaminated oil to do the job of lubricating an engine for thousands of miles will spell doom for your internal components.

Your engine oil also cools and lubricates your turbo! Didn’t think of that did you! That thing is spinning at a bagillion (diesel technical term, it meas a lot) miles per hour It needs good clean 15W30 to run through it’s veins. I would say a lot turbo failure comes from poor regular maintenance.

Save money some where else!

Good advice

  • Look up the specific specifications for your diesel and follow them as best as you can. You can never go wrong doing what the engine maker says to do.

  • Check the oil often! You can’t go wrong taking a look. Often our equipment is very expensive. As a matter of fact, if it has a diesel engine guaranteed it costs a lot of money. You should take the time to check the oil before each use. No oil is a disaster and diesels always have leaks. Look for good color and thickness or viscosity. It should have a bit of tackiness if it drips like water, that’s not good.

  • Have the oil sent out for analysis It doesn’t cost as much as you think. 20 or 30 bucks and it could save a major repair. I once caught a leaking head early enough to keep from major damage.

  • Buy a decent oil You cant expect cheap oil to last or even do a good job. Listen treat oil like ketchup. You wouldn’t buy off brand ketchup. Thats gross! Buy the good stuff.

Specific Manufacture Recommendations

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John Coker

Johnathan Coker is a ASE and EVT Certified Mechanic. He is married with two kids and lives in sunny Florida. He loves taking stuff apart and teaching others how he messed it up.

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