What Causes Engine Corrosion and How Can You Avoid It?

Because it’s hard to detect and takes a long time to develop, engine corrosion can be tricky to manage. Most drivers probably don’t even consider the long-term health of their car’s engine, but it’s worth thinking about if you want to avoid faults and keep things running as long as possible.

Depending on how often you service and maintain your car, your engine may already be suffering from corrosion. But don’t panic, as with the right maintenance and protection you can slow the rate of corrosion and keep your car in a clean bill of health.

At Prestone, we want to help you look after your car mile after mile, which is why we’ve put together this guide on engine corrosion and how to avoid it.


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What Causes Engine Corrosion?

There are several causes of engine corrosion, affecting different components and areas under the bonnet. Just like rust, the onset of corrosion takes a long time to develop and is mainly caused by harmful chemical reactions within the engine.

Let’s break down the leading causes of corrosion and the areas of the engine most affected:

  • High-temperature corrosion – if your car is running too hot, there’s a risk of oxidisation, which can lead to rust in some parts of the engine. High-temperature corrosion is caused by friction, which happens as a result of low or poor-quality engine oil.
  • Crevice corrosion – occurs in small areas and gaps around the engine, including seals and gaskets. This type of corrosion is caused by deposits, which gradually degrade components over time.car engine
  • Chemical corrosion – chemical corrosion happens when harmful compounds are generated in the engine, for example, sulphuric acid. Such compounds are created when fuel and oil mix with water molecules, and their effects can be harmful to some engine components.
  • Galvanic corrosion – this happens as result of an electrochemical reaction, when two different metals come in electrical contact with each other. This isn’t something to worry about, as it’s an unavoidable process and has minimal impact on the car’s longevity.

What Problems Can Engine Corrosion Cause?

If left unchecked, engine corrosion can lead to breakdowns and expensive repair bills; it could also limit the lifespan of your car. Let’s take a look at some of the common faults which may occur as a result of engine corrosion:

  • Overheating – when there’s corrosion in the engine, you may encounter a cycle of overheating issues. It’s caused by friction which gets worse over time as a result of rust and corrosion, and it may lead to leaks or other damage within the cooling system.
  • Reduced MPG and efficiency – engine corrosion can cause a range of engine running problems, including misfires and reduced efficiency. That’s because corrosion and deposits interfere with the combustion cycle, meaning that the engine can’t process air and fuel at its normal rate.
  • Faulty fuel injectors – a common type of crevice corrosion occurs in the fuel injectors, which can get clogged with deposits and develop faults over time. This leads to a drop in engine efficiency.
  • Blocked fuel and oil filters – rust and deposits in engine oil can result in ‘sludge’, which blocks the fuel and oil filters and can cause a range of faults and issues.
  • Reduced oil lifespan– you may find that you need to replace engine oil more frequently because of deposits within the system, which change its colour and consistency, and its ability to lubricate the engine.

engine coolantHow to Prevent Engine Corrosion

While modern engines are designed to deal with wear and tear, you can extend the life of your car by doing your best to prevent corrosion. Here are our essential tips on how to prevent engine corrosion:

  • Stick to your car’s service schedule – a full annual service is an effective way to control engine corrosion. Changing the oil and oil filter every 12 months, and checking it in the interim, gives you peace of mind that your engine is protected and lubricated.
  • Check the coolant/antifreeze level regularly – check the reservoir often to make sure there’s enough clean coolant in the system. As an additional step, check the condition of the fluid with a coolant/antifreeze tester.
  • Use high-performance coolant/antifreeze – modern coolant/antifreeze contains additional compounds which are designed to offer corrosion protection within the cooling system. Always use a high-performance coolant/antifreeze to benefit from this added protection. Prestone coolant/antifreeze has been developed to offer superior protection against corrosion and comes with a 10-year guarantee.
  • Maintain the fuel system – the fuel system has a direct impact on the health of your car’s engine, and it’s from here that moisture and deposits get into your engine. As a rule, make sure the fuel filter is changed every 20,000 miles, particularly if it’s an older car. You should also avoid driving on empty, as this can draw deposits into the engine. Fuel system additives and cleaners can help keep the fuel injectors in good condition.
  • Flush the cooling system – flushing the cooling system is an important step in maintaining the engine and reducing corrosion. If you notice a change in the colour of the coolant/antifreeze in the reservoir, this indicates that it’s picked up deposits in the cooling system, so it’s time to give it a flush. Follow our guide on how to flush your car’s cooling system in eight simple steps.

Engine corrosion can cause problems for your car, but with the right maintenance and protective measures you can make sure it’s always in good health. For more tips and advice, check out the Prestone blog or visit our homepage to learn about our high-performance car maintenance products.

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