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Engine flushing. Is it even worth it and if yes, how should it be done?

Engine flushing. Is it even worth it and if yes, how should it be done?

There are many myths related to engine flushing. Some people do not recommend them and some do. What is the golden mean and what is the truth?  


It is impossible to talk about engine flushing without discussing the reason that contamination occurs in the engine is and how it can be removed. Oil system contamination can be divided into high-temperature and low-temperature contamination (Fig. 1 and 2). As the names indicate, this contamination is related to the oil temperature at which it is formed. Contamination can be accelerated by late or missed oil changes, frequently driving short distances or driving in urban conditions (high traffic), driving at a high rotational speed or under heavy load or even with a low level of fuel.  

What are the consequences of driving with a contaminated engine?
Having contaminants in the oil system always reduces the service life of the engine. This can happen much earlier than an extreme case of the oil system becoming blocked. Contaminants reduce the flow of oil. In most engines, the lubrication system is controlled using pressure. The reduced cross-sections of the main oil line create adequate pressure, but much less oil as a lubricating and cooling medium reaches the individual friction nodes. This occurrence significantly increases the wear and tear of the engine and fuel efficiency. 
Fig. 1 Low-temperature oil contamination (source: Castrol)
Fig. 1 Low-temperature oil contamination (source: Castrol) 
Fig. 2 High-temperature contamination of the lubrication system
Fig. 2 High-temperature contamination of the lubrication system 
How can this type of contamination be removed?

If low-temperature contamination is found, it should be removed via the engine and oil through prolonged engine use at normal oil operating temperature (~90°C). If such engine operation is not possible, it is recommended to use Castrol Engine Shampoo – a flush that will dissolve contamination within 10 minutes of idling. The contaminants can then be removed during the oil change (right after the flushing process). Reoccurrence of this type of contamination can happen if the vehicle is constantly driven with underheated oil (short distances/urban conditions) or if engine failure occurs (e.g. coolant penetrating into the engine). 


 The main root causes of high-temperature contamination are engine load (high oil temperature tends towards oxidation; a large load also leads to higher production of particulate matter, which contaminates the oil) and long oil change intervals or an absence of oil changes. High-temperature oil contamination is significantly harder to remove. As a long-term preventative, oils with increased cleaning capabilities, such as the Castrol GTX or GTX Ultraclean product range, can be used when carrying out a service. This service method can also prevent the accumulation of contaminants during heavier engine use. Similarly to low-temperature contamination, using a flush may be a quicker solution. The mechanism of action of the cleaning agent is very important in the event of hard, high-temperature contamination. With solvent-based agents, it is possible that contaminants could separate from the engine components and block the oiling system. A better choice of flush would be detergent-based, which can significantly less aggressively dissolve the contaminants into a soft liquid and is 100% safer. This type of agent, like the previously mentioned Castrol Engine Shampoo, is 100% safe and, thanks to detergent technology, can be used without any worries, even in motorcycles with wet clutches which could be damaged by detergent flushes.  


Castrol Engine Shampoo is one of only a few flushes tested for use in motorcycles with wet clutches and it has JASO MA2 approval. It has also undergone sealing compatibility tests and is certified for full compatibility with all types of seals used in automotive lubrication systems. 

Is it worth it? If yes, when should you offer your customer a system flush?

Definitely, yes. Especially in vehicles where there have been long oil change intervals, there is no service history, contamination has been found behind the plug or when the engine has been under load – for example, it has been used in mountainous areas, or has been heavily loaded or towing. In these circumstances it is always worth suggesting such a service. It takes practically no time for the workshop to add this procedure to an oil change. Pouring in the flush and letting the engine run for 10 minutes before the oil is discharged can be done while the work station is being prepared and the vehicle is placed on the lift.  

 

Note: always observe the flushing agent manufacturer’s recommendations.