Regular oil changes are essential to maintain the condition of a 4-stroke engine, but removing the drain bolt does not necessarily drain all the oil. In some cases, oil that remains in the engine little by little over a long period of time can have a detrimental effect on the engine. To check for this, it is useful to remove the oil pan and check the inside.
Even if the drain bolt is attached to the bottom of the crankcase, the engine oil may not empty
The theory is that oil should be changed a short time after driving or after the oil temperature has been raised by idling. However, be careful not to change the oil at too high a temperature, as there is a risk of burns.
Oil changes for 4-stroke engines are performed according to the instructions in the instruction manual or the user's own decision, such as every 3,000 km or every six months. Whether you ask a store or do it yourself, the general procedure is to drain out the old oil from the drain bolt after warming up the engine to some extent, shake the vehicle back and forth and side to side, and wait a while before installing the bolt and injecting new oil.
The amount of oil required for an oil change is listed in the owner's manual, service manual, or on a sticker attached to the engine, which may indicate multiple values such as "total capacity," "capacity at oil change," and "capacity at oil and oil filter change.
It is understandable that "oil change capacity" and "oil and oil filter change capacity" are different among these. This is because, regardless of whether it is a cartridge type or an engine built-in type, if the oil filter is removed, more oil is discharged as a result. Then, what is the difference between "total capacity" and "capacity at oil change"?
This is the difference between the amount of oil to be lubricated when all parts are almost dry (with only a small amount of rust-preventing oil on them) when the engine is assembled and the amount of oil to be lubricated after the oil that is already in the engine is drained. This shows that the full volume of engine oil cannot be completely drained just by removing the drain bolt.
Certainly, there are engines where the camshaft holders and combustion chamber area are soaked in oil even after the drain bolts are removed, and it is unlikely that the viscous oil will flow down cleanly to the bottom of the engine. Furthermore, the oil drain is located at the lowest point in the engine, and not all of the oil in there will drain out.
Some engines for the latest supersport models are deep enough to allow the oil pump to suck up oil even when cornering at deep bank angles. However, many old-fashioned engines, in which the muffler is located under the crankcase, have flat oil pans.
Old oil tends to remain inside the engine in these oil pans. Since oil remains that cannot be drained out of the drain in any way, there is a difference between the "total capacity" and the "capacity at oil change." Normally, however, if the capacity at oil change is observed, the amount of oil poured will not be excessive.
However, depending on the year of the bike, the oil used, and the type of additive used when actively using additives, impurities may be generated and remain in the oil pan.
The example shown here is of a Kawasaki Z1 series engine that had been immobile for a long period of time. When the oil pan was removed after draining the oil, there was a large accumulation of gelatinous foreign matter inside. I don't know if this is a transformation of the additive contained in the engine oil, or if it is a component of an additive sold on the market, or if the oil itself becomes like this, or if it would not have been transformed if the engine had not been immobile for a period of time. The reason for this is that the
If all the oil in the oil pan was drained out every time oil was drained from the drain area, perhaps these foreign substances would not have been generated, but if even a small amount remains, it is possible that it could become a mountain of dust.
- Point 1 - If the engine oil quantity has "full capacity" and "capacity at oil change", residual content remains inside the engine at the time of oil change.
- Point 2 - A combination of various conditions can alter the oil remaining inside the engine.
Whether or not the oil pan can be removed depends on the structure of the engine.
The oil pan of the Kawasaki Z1 series engine can be removed without interfering with the frame as long as the muffler is removed. The oil pan is divided into two chambers, one for the crankshaft and the other for the transmission, with the oil filter element penetrating the crankshaft.
These two chambers are not clearly separated, but there is a maze-like partition that creates a certain resistance for the oil flowing in the bottom of the oil pan. Therefore, the gel that has accumulated in the lower part of the transmission? Sludge? The foreign matter, which looked like a "foreign substance," did not flow to the oil drain bolt and continued to accumulate in the same place.
The buildup was a grease-like substance dissolved in engine oil. Whether it was an additive component in the engine oil or an after-market oil additive, I have no idea since this is an out-of-print car that I purchased used. If it is clear that the engine has been overhauled, there is no need to worry, but if the history is unknown, it might be better to check just in case.
It is impossible to tell what is left in the oil pan until it is opened, but then some users may want to remove it to see what is inside. However, whether or not this is possible depends on the structure of the engine.
The Kawasaki Z1 series engine shown here has a crankcase that divides into upper and lower sections, and the oil pan is attached to the lower part of the lower case as a lid, so it can be removed on its own if the muffler or other components that interfere with the lower part of the oil pan are removed. The oil pan can be removed by itself by removing the muffler, etc. that are in the way at the bottom of the oil pan.
In contrast, the left-right split crankcases of the Honda Monkey and other models do not have an oil pan at the bottom of the crankcase. The oil flows easily toward the drain bolt, but if you want to check the remaining oil, you have to disassemble the crankcase, or in other words, overhaul the engine.
- Point 1: Models with removable oil pans can be checked inside, but some engines do not have removable oil pans.
Check the oil pump strainer after removing the oil pan.
The condition of the oil pan naturally makes one worry about the condition of the oil pump. Simply spraying parts cleaner on the oil pump mounted on the bottom of the crankcase will clean it to some extent, but it is so dirty that it is not enough to reassure us.
About 2/3 of the strainer net was covered with dirt. Since this vehicle had been immobile for a long time, it must have been in this condition over a long period of time, but there was no doubt that so much dirt and foreign matter had accumulated on the vehicle while it was running. Whether it is dirt or foreign matter, it does not just suddenly appear one day but accumulates gradually even if the oil is changed regularly. Considering this, it is beneficial to the engine to check the oil pan and oil pump at some point.
If the foreign matter has accumulated in the oil pan, the oil pump should also be checked. The strainer net of this Z series engine was also covered with gelatinous foreign matter mixed with obvious debris. The gelatinous substance may turn into liquid when the oil temperature rises, but of course, we would not feel comfortable starting the engine in this condition.
If the oil temperature rises but the net surface remains like this, the amount of oil the oil pump can pump may be affected. Then the possibility that poor lubrication may occur even after the engine oil is changed cannot be ruled out.
In a word, good oil management is not an easy task for old or out-of-print vehicles. If the bike was purchased new, you can keep track of the engine oil used, but if it was acquired as a used bike, the history is unknown. Depending on the compatibility of the engine oil and the additives on the market, the oil itself may change in some way and become altered.
Since the condition of the oil pan varies depending on the maintenance history and management, it cannot be said that the oil pan needs to be checked generally because of the number of years it has been there, but it is good to know that the residue that is not removed even if the engine oil is changed on a regular basis may be altered in this way.
- Point 1 - When the oil pan is removed, check the condition of the oil pump as well.
