How does sludge build up in an engine?
Tuesday 4th February 2025
Treacle is great to eat, but it’s not so great in your engine. “Engine sludge” can lead to catastrophic engine failure. Find out more about this toxic substance, how it can shorten your car’s lifespan and what you can do to prevent it.
What is engine sludge?
Engine sludge – or oil sludge – is the result of a mixture of impurities in and around your engine which looks like tar. It’s murky, viscous and, well… sludgy.
If it goes unnoticed in your car, it can lead to poor vehicle performance, or your car can completely pack up.
How does engine sludge occur?
No matter what type of oil your car needs, whether regular or synthetic, it’s not supposed to get dirty. It becomes contaminated from contact with oxygen (oxidisation), which converts the oil into a thicker, detrimental substance.
Your oil also loses its purity over time from general grit, dirt and metal fragments it collects through the lubrication process. The invasion of sludge is slow, concealed, and cumulative, which is why regular oil maintenance checks are vital.
Symptoms of engine sludge
- Dashboard warnings like low oil pressure.
- Falling mileage.
- Poor engine performance and overheats often.
- Unusual noises like clicks or knocks.
- Engine failure.
- Exhaust smoke.
- Misfires and hesitation.
Causes of engine sludge
- Frequent and long-term idling.
- Stop-and-go driving.
- Low maintenance and low mileage.
- Excessive heat.
- Poor engine-combustion efficiency.
- Long periods of inactivity.
- Antifreeze contamination.
- Faulty seals or clogged or damaged oil filter.
- Adding too much oil to the oil sump.
Why does sludge damage engines?
Essentially, oil sludge suffocates your engine. Sludge blocks oil passages and hinders the circulation of oil to the moving parts of your engine. Instead of it being cool and lubricated, it has to work harder to function. There’s the threat of the engine overheating, increased friction on internal parts and complete engine seizure.
What can I do to prevent engine sludge?
It doesn’t matter what vehicle you have, how you drive or whatever driving habits you have – engine sludge doesn’t discriminate. An engine with sludge can be fixed, but it’s easier to prevent than to cure.
Here are some actions to prevent engine sludge:
- regular oil changes with high quality products
- proper engine operation
- use the correct oil for your vehicle
- don’t ignore dashboard warnings
- avoid DIY – the engine should be inspected and dismantled properly
- drive with care
Can oil supplements help with oil sludge?
Oil supplements are designed to extend the life of your engine and improve fuel economy. They also offer other benefits:
- Strengthens lubrication
- Removes contaminants
- Protects against corrosion
How can Formula One Autocentres help?
Maintain your car’s value with Formula One Autocentres’ oil supplement, or if you think engine sludge has already set in, contact our team from your local centre.
