An engine flush can be a useful thing for removing sludge and oil deposits that build up in an oil sump. They work within some relatively-simple principles. Chemical cleaning agents are poured into the engine, which is then idled to ensure the cleaning agents reach the areas that the oil normally travels to. The oil is then drained, which also drains out the cleaning agents and the sludge and deposits they have cleaned.
Engine flush products can offer some benefits to diesel engines. They can help oil flow more freely by clearing out deposits that may have ended up clogging some of the narrow oil passages. Once freed, the oil flows as freely as it should, saving wear and tear on the engine.
When should you consider an engine flush?
Engine flushes aren’t something that need to be done with every oil change. Diesel engine manufacturers will advise that they recommend against an engine flush for vehicles that have had regular oil changes. There’s more than a grain of truth in their recommendations. Regular oil changes will remove most of the oil deposits that could become problems over time.
But many vehicles don’t have their oil changed at the intervals recommended. And if these vehicles take a lot of short trips, they are twice as likely to accumulate oil sludge over time. In fact, there are several instances where an engine flush is more likely to have benefit in a diesel engine:
Vehicles with unknown maintenance records – if you don’t know if the oil has been changed regularly (such as if you bought an older used vehicle), an engine flush is probably a good idea.
Vehicles with longer times between oil changes – nobody says you have to change oil every 3000 miles. You should be doing it according to the recommendations in the owners’ manual. But regularly waiting longer intervals before changing the oil greatly increases the change of oil sludge forming. So it’s a good idea to run an engine flush every so often to get rid of that harmful sludge.
If the vehicle has had recent engine work – engine flushes can be a good idea here because they can remove leftover particulate that may be hanging around. This is a good idea to do before you put fresh oil in the engine and proceed with the rest of its life.
Recommendations for Diesel Engines
Are the engine flush recommendations different for diesel vehicles vs. gasoline engines? Not especially. Diesel vehicles can tend to have longer oil change intervals, which does lead to the greater chance of creating sludge in the engine. But if you stick to the manufacturer recommendations, there’s not really an overriding need for engine flush even in a diesel engine. If you find yourself in a situation like the ones above, you may want to consider an engine flush for your diesel vehicle.
No matter what kind of vehicle or engine you have, an engine flush treatment is no substitute for taking proper care with your oil changes intervals. Changing your oil when it’s recommended. Oh, and no matter what, always change your filter whenever you change the oil. This is especially true if you’re doing an engine flush.
You may be interested in these other posts on Diesel and Lubrication:
- Lubrication of Turbochargers
- Engine Oil Consumption - James on Engines #1
- Accidentally mixing gasoline and diesel fuel - What happens then?
This post was published on September 6, 2016 and was updated on October 13, 2017.