Flushing the engine when changing the oil is not a 100% necessary procedure. Moreover, it is unsafe. But under certain conditions and the right approach, flushing really helps to improve the condition of the lubrication system. This material discusses the main objectives of this procedure, its feasibility, possible dangers, as well as four ways to perform.

Why is it necessary to flush the engine before changing the oil?

The general purpose of flushing the engine is to dissolve and remove deposits from the lubrication system formed from dirty, burnt, not changed for a long time, or simply low-quality oil. In more detail, three tasks stand out:

  1. Channel cleaning. Blockage of thin holes and crevices leads to the fact that the lubricant does not spread everywhere, or in insufficient volume.
  2. Improved heat dissipation. Deposits in the form of soot impair heat removal from rubbing parts. The lack or complete absence of lubrication is guaranteed to lead to overheating.
  3. Prevention of oil starvation. To avoid it, the lubricant must normally be taken from the sump, pass through the filter, and then be properly distributed through the channels and slots to all rubbing surfaces.

Also, many are familiar with the situation when, after filling in fresh engine oil and checking its level, traces of mining are observed on the dipstick. This is a bad signal, and flushing can get rid of it.

Principles of flushing the lubrication system

The principle of oil mist formation
The principle of oil mist formation

The process of flushing the lubrication system is based on three main principles:

  1. Washing away of simple deposits. You see something similar clearly when you wash any oily parts in gasoline or diesel fuel. Such dirt is easily removed, and you don’t even need to rub anything. The main plaque inside the lubrication system of a well-groomed motor is just that.
  2. Liquefaction of sparingly soluble soot. Formed for several reasons. This may be soot, a mixture of mining with metal dust, thickened due to the statute of limitations of the additive. To wash off such a plaque, you need an alkali.
  3. Removal of washed and liquefied dirt. It is not enough to remove deposits from the surface of parts and channels. The dirt that has flowed into the pan must be completely removed, otherwise it will mix with fresh oil, and you will see it on the dipstick immediately after replacement.

Alkali is the main active ingredient that is present in various motor flushing products. It effectively copes with the liquefaction of hardened deposits, but it has an extremely aggressive effect on rubber products (seals, o-rings, gaskets, caps).

Engine flush methods

There are three ways to flush the lubrication system of an internal combustion engine:

  1. Flushing engine oil.
  2. Concentrated detergent.
  3. Diesel fuel.

Let's consider all three options in more detail.

Flushing engine oil

It is a relatively inexpensive oil, which contains a small amount of alkali. Other additives with "miracle effects" may also be present. Flushing the engine with this method is performed according to the following algorithm:

  1. The engine warms up to operating temperature.
  2. The used oil is drained.
  3. Flushing engine oil is poured.
  4. The engine is operated in sparing modes for a couple of days.
  5. The flushing oil is drained.
  6. Regular engine oil is poured.

Motorists rarely prefer this method of flushing the engine for two reasons. Firstly, although flushing oil is cheaper than usual, it costs far from three kopecks. Secondly, the replacement procedure stretches for several days, during which it is impossible to fully operate the machine.

There are also benefits. The main one is that flushing in this way is the safest for the motor. Including, for the rubber products mentioned above.

Concentrated flushing agent

Probably the most popular way among motorists. It is performed as follows:

  1. The engine warms up to operating temperature.
  2. A concentrated flush is poured into the lubrication system.
  3. The motor is allowed to run at idle for 5-15 minutes.
  4. Processing merges.
  5. Filled with fresh engine oil.

The advantages of this method are obvious - fast, relatively inexpensive, very effective. Only one point should be attributed to the shortcomings. The market is full of fake concentrates that either do not wash off anything, or split rubber products into atoms in the motor.

Diesel fuel

Folk or old-fashioned method, which can be called cheap and relatively safe. It is performed according to the following algorithm:

  1. The engine warms up to operating temperature.
  2. Processing merges.
  3. Diesel fuel is poured into the lubrication system in a volume equal to the volume of engine oil being poured.
  4. The engine is allowed to idle for no more than 5 minutes.
  5. Dirty diesel fuel merges.
  6. Regular engine oil is poured.

It should be noted right away that this method is effective only when there are no sparingly soluble deposits in the motor. Usually, if you change your oil regularly, and don't pour outright deshman, then this kind of dirt should not be in your engine.

Oil pump
Oil pump

Using this method of flushing the engine, drain dirty diesel fuel as carefully as possible. It is better to use a special suction for this, and not a drain hole. Otherwise, the remaining diesel fuel (with dirt) will mix with the fresh oil, causing it to become thinner than it should be.

Unacceptable ways to flush the engine

No adequate car owner will use any of the following, but still:

  • solvent;
  • White Spirit;
  • other solvents for paints and varnishes;
  • dimexide;
  • pure alkali;
  • soda;
  • boiling water;
  • detergents for dishes;
  • petrol.

It is strictly forbidden to use for flushing the engine lubrication system!

10 reasons not to flush your engine when changing oil

Look in any engine manual and you won't find a word about flushing in any of them. All you need to do is change the engine oil regularly and in a timely manner.

If this principle is considered in more detail, then it is not necessary to flush the engine when changing the oil when:

  1. Oil change is carried out every 10,000 km or more often.
  2. Oil change is carried out at least once a year.
  3. In the drained mining, you do not see any impurities.
  4. It does not resemble water in consistency.
  5. You are not using the cheapest nameless oil.
  6. Through the oil filler neck you can see the shiny parts of the gas distribution mechanism.
  7. The oil level is checked regularly.
  8. The engine was not subjected to critical overheating.
  9. The car does not constantly drive through sand, mud and dusty fields.
  10. You change the oil in a particular engine not for the first time.

If you put a conditional check mark next to each item, you do not need to flush the engine when changing the oil.

7 reasons to flush your engine

Dirty oil on dipstick
Dirty oil on dipstick

Now consider several reasons when flushing does not interfere with the engine:

  1. You just bought a car in the secondary market.
  2. In the drained mining there is foam, colored or white stains.
  3. With working out, clots of incomprehensible things fall out of the drain hole.
  4. Deposits are visible on the parts of the gas distribution mechanism through the oil filler neck.
  5. You filled in fresh oil, and you see that it is dirty on the dipstick.
  6. You haven't changed your oil in over a year.
  7. Since the last oil change, the car has traveled much more than 10,000 km.

It is also worth thinking about flushing if the day before you saved on engine oil, at least once the level turned out to be less than the bottom mark, the engine overheated or was operated in harsh conditions.

VIDEO: engine oil flush


Trouble in the engine pan
Trouble in the engine pan

There is nothing inadequate in flushing the engine when changing the oil, if you approach the matter wisely. Firstly, you do not need to do this only for prevention. Second, use only acceptable methods and means. Thirdly, after flushing, it is extremely important to make sure that there is no dirt or jelly-like substance left in the pan, which can clog the oil intake mesh.