When car owners change the engine oil, they all want to lift the car high and drain the engine oil cleanly. Some car owners will still find that when adding engine oil, there will often be some left in a barrel of new oil that cannot be added. Different cars have different amounts left, some more and some less. Is it because the oil was not drained cleanly?
There are two reasons for this problem:
First, no matter where you change it, the oil will flow out naturally by gravity. Due to the angle of the oil outlet and the irregular structure of the oil pan, there is always a part of the oil that cannot flow out naturally. Because the engine oil has been used for a long time, it contains many impurities and cannot be completely cleaned. For example, if you put sand in a large basin of water and then drill a hole in the bottom of the basin, you will find that some of the water and sand cannot flow out. The same is true for engine oil. You can see when you open the oil pan. For example, there is still some engine oil on the crankshaft and connecting rod. This oil cannot be drained away by gravity. Moreover, when the 4S shop is busy, it will not let you put the oil in for a long time. In this way, there will be too much old oil and less new oil will be added. So it's normal to have a little engine oil left.
In addition, there are many ways to lubricate the engine. Some parts cannot be lubricated by the oil passage due to mechanical structure reasons. They can only rely on the constant circular motion of the crankshaft balance weight and the bottom of the connecting rod to splash the oil into the lubrication areas, such as valves, top pillars, etc. If the cylinder wall, etc. are all cleaned, the engine will be damaged when starting.
Second, there are some unscrupulous masters who do not drain the engine oil completely and sell the remaining oil. There are only two options for buying engine oil, 1L or 4L. For example, for Passat and Magotan, add 4.8L, leaving 200ml. The extra 200ml will be retained. If 5 Passats come for maintenance today, isn't this just right? I collected 1L, and suddenly I had a bottle. For the Sagitar, you only need two cars to make up 1L. So, those car owners who go to the store for maintenance and just throw away the keys without looking at them, do you feel some knee pain? Then the extra 1L can be sold, but not all car repairmen are like this, after all, they are a minority.
Will not draining the oil cleanly cause damage to the engine?
As mentioned above, engine oil cannot be drained cleanly by gravity. Car owners are concerned about whether the remaining old oil will damage the engine. In fact, you don't have to worry at all. Engine oil has the functions of cleaning, lubrication, cooling, anti-corrosion, sealing, etc. The metal debris produced by the internal wear of the engine can be retained in the oil pan with the circulation of the oil, because the oil pump in the oil pan will When the oil is transported to the upper part of the engine, the oil will be filtered, and then the oil will enter the lubricating oil passage, so there will be no damage to the inside of the engine.
During engine operation, engine oil is affected by the fuel combustion temperature and the catalytic effects of various media and metals. It gradually deteriorates and ages, producing various substances harmful to the engine such as carbon deposits, paint films, and sludge. Therefore, the lubrication system must be cleaned regularly. Only residual engine oil can ensure the "health" of the engine!
So how to store remaining engine oil?
Reasons for engine oil deterioration:
Moisture: Under normal circumstances, the water content in engine oil is below 0.03%. When the water content exceeds 0.1%, the additives in the engine oil will become ineffective and accelerate the oxidation process of the engine oil. The organic acids generated by the oxidation of engine oil and the acidic oxides in the engine exhaust gas react with water to generate inorganic acids. These acids increase engine corrosion.
Then there is oxygen: Oxygen also affects various additives in engine oil, and don't think that only good engine oils have many additives. There are additives in all engine oils. Especially when exposed to sunlight or high temperatures, oxygen in the air reacts faster with engine oil.
There are also impurities: Impurities mainly affect the cleanliness of the engine oil. Impurities mixed in the engine oil will affect the lubrication effect of the engine oil, and even cause abnormal wear of the engine, thereby affecting its sealing performance and even burning the engine oil.
If the car owner fills this kind of deteriorated engine oil into the vehicle, the parts in the engine that need lubrication and cooling will not be adequately protected, and the engine load and wear will increase, eventually causing engine damage and requiring early overhaul.
preservation method:
1. Cover the mouth of the engine oil bottle with a layer of plastic film, and then screw on the oil bottle cap. Pay attention to keeping the bottle mouth sealed, choose a thicker plastic film, and then drip wax to seal it, otherwise it will be difficult to isolate the air.
2. Place the sealed engine oil in a cool, dry place to prevent the oil from oxidation and deterioration, such as in a corner. Of course, many car owners like to put it in the trunk, which is okay, just in case of emergency.
3. Engine oil that has been sealed for a long time will inevitably contain moisture and impurities. Do not shake it before use. When adding engine oil, do not pour it all in. There will be a small amount of water or impurities at the bottom of the bottle. Adding it to the engine will affect its performance or even have adverse effects. So add engine oil and keep a little part of the bottom of the bottle, so that all the water and impurities can stay in the bottle!