What are good drain intervals for Heavy Duty?

Wolf Lubricants - heavy duty, techncial expertise, engine oil, motor oil

Whether it is oil choice or driving conditions, the stresses on oil affect the intervals of oil drains. How do you know how to weight these factors up? Find out.

If you have ever had a heavy duty customer come in asking how often an oil change should occur, knowing how to uniquely address their question can be a hard answer to give. 

The factors that go into the oil change calculus depend on a number of competing factors. Gone are the days where heavy duty oil draining needed to be done every 8,000 km or so. With the standards of engines and lubricants continually on the rise there are a number of factors to consider when giving your customer the right information. The correct answer can vary anywhere from every 10,000 km to as much as 80,000-100,000 km. 

Don’t forget: Drain interval is expressed in kilometres or months! Replacing the oil after, for example, 24 months is obligatory, even if the maximum amount of kilometres has not been reached.

How can you tell what is the ideal drain interval for heavy duty?

The factors to consider include:

  • Engine type and age
  • Service conditions (haul and load)
  • Oil quality 
  • Fuel quality and consumption
  • Road conditions (hilly or flat)
  • …and many others.

The Starting Line: Know your customer, know their vehicle.

Each vehicle manufacturer determines the drain interval on the basis of extended field-testing, statistical data and experience. Intervals mentioned in service bulletins refer to standardized conditions. 

In reality, the recommended drain will often have to be adapted depending on a number of important factors. 

Before considering all the factors you need to draw a baseline. You may want to take into consideration the type of engine and its age. A good rule of thumb is to understand that the older the engine the higher the risk for engine contaminants, which shortens the intervals between needed oil changes. You need to nail down your customer’s oil change habits.

Things to consider that may shorten the time needed between oil changes:

  • Do they buy high quality oil and filtration?
    • Low quality = shorter intervals
  • How dirty is the oil coming out?
  • How are those pistons faring? 
    • Lots of combustion zone wear is a sign of a need for more frequent oil changes
  • How often do they need to top up?
    • Low fuel economy and oil efficiency is a good indicator of a need to change more often
  • Smog test?
    • A higher level of tail pipe emissions is another solid indicator for frequent oil changes

Where are you driving?

Driving in extreme temperatures or on dirty, dusty roads will put high stress on the oil and will shorten the oil drain. Long haul heavy-duty vehicles may reach a drain of up to 100,000 km. The more demanding short-haul operations typical for city transport will shorten the drain interval. 

Just like a team doctor needs to consider the weather for an athlete, a driver needs to remember that the conditions matter.

  • Do they have a cold start?
    • Low temperatures at engine start put a heavy demand on lubricants.
  • Is it hot out?
    • High ambient temperatures will affect oil life.
  • Where are they driving?
    • Intake of dirt isn’t just from contaminants within the engine. You need to find out the quality of the road surfaces as well.
  • Hilly or flat? Heavy loads or light?

The take home message here is that the harder your engine works, the more strain is put on the oil. The higher the strain, the shorter the oil drain interval.

Doing the math:

There is no calculator that exists to weigh the multiple factors that go into the oil drain calculus down to a mathematical certainty. However, it is important to stress the choice of oil quality to customers. 

Of course, you aren’t left out in the cold. For heavy duty fleets or large industrial equipment there is the possibility of performing a used oil analysis. A set of chemical (base number, additive content, etc.) and physical tests (viscosity) can give an indication if there is any usable life left in the oil.

Finally higher quality oil increases the time between full oil drains. Solid protection allows drivers some comfort in not having to continually perform the oil drain calculus. Manufacturers like Wolf Oil continuously work towards a longer oil drain interval. But it is of the highest importance to consult manufacturers documentation before taking decisions related to extension of the drain. 


  • Each vehicle manufacturer determines the drain interval.
  • In reality, the recommended drain will often have to be adapted depending on a number of important factors. 
  • For heavy duty fleets or large industrial equipment there is the possibility of performing a used oil analysis.