Fuel dilution of engine oil: an underestimated problem in petrol and hybrid engines
Modern hybrid engines are more powerful and efficient than ever.
At the same time, stricter emission standards, direct injection, and changed driving patterns create new maintenance challenges. One of the most underestimated of these is fuel dilution of the engine oil.
Many motorists do not notice it immediately, but fuel getting into the engine oil can affect the quality of the oil and contribute to internal contamination of the oil system.
What is fuel dilution?
Fuel dilution occurs when a small amount of unburned gasoline passes the piston rings into the crankcase and mixes with the engine oil.
A limited amount is normal in any internal combustion engine. Problems arise when this process continues to repeat over a prolonged period, causing contamination to accumulate.
The following conditions, in particular, increase the risk of fuel dilution:
- Frequent short trips
- Regular cold starts
- City traffic with frequent stops and starts
- Prolonged idling
- Engines with direct injection
Why is this a problem?
Motor oil has several important functions: lubricating, cooling, cleaning, and protecting against wear.
When gasoline mixes with the oil, it can lead to:
- Reduced lubricating effect
- Accelerated oil aging
- Formation of sludge and deposits
- Contamination of the oil system
- Increased/accelerated wear of engine parts
Over time, these deposits can accumulate in oil channels, valve trains, and other critical parts of the engine.
Extra attention for hybrid engines
Although fuel dilution can occur in all petrol engines, hybrid vehicles deserve extra attention.
In a hybrid car, the petrol engine is regularly switched on and off. As a result, the engine rarely runs at full operating temperatures.
This can mean that:
- Moisture evaporates from the oil less quickly
- Unburned fuel remains in the oil for longer periods
- Internal contamination builts up more quickly
Precisely for these reasons, preventive servicing of the oil system in hybrid cars is especially important.
Recognizing possible fuel dilution
Fuel dilution is not always immediately visible, but possible signs may include:
- Rising oil levels
- Strong gasoline (petrol) smell coming from the oil
- Dark or heavily contaminated oil
- More sludge visible under the oil filler cap
- More frequent oil changes
Oil change by fuel dilution
If contamination is already present in the oil system, Tec4 Oil System Cleaner can be applied prior to an oil change. This product helps loosen deposits and sludge, allowing contamination to be removed along with the old oil during the oil change.
This provides the new engine oil with a cleaner base to function optimally.
Would you like to know more about the importance of a flush before an oil change? Then read this article.
Continuous cleaning with Tec4 Long Life Oil System Cleaner
For long-lasting protection and preventive servicing, Tec4 Long Life Oil System Cleaner offers a different approach. This product is to be added to the (clean) new engine oil and supports continuous cleaning of the lubrication system (oil system) whilst driving. It helps limit new contamination and supports optimal lubrication of the system in between servicing periods.
Especially for vehicles that make many short trips or for hybrid vehicles, this continous cleaning additive can be a valuable addition to your regular oil service.
Preventive service prevents problems
Fuel dilution is not a problem that occurs only in old vehicles. Modern petrol and hybrid engines, in particular, can be affected by it due to their specific operating conditions.
By paying timely attention to the oil system and using the right cleaning products, you prevent contamination from building up unchecked.
Good service does not start only when problems arise, but actually helps prevent them.
Want to know more about engine contamination? Then read this article.