The permissible normal rate of engine oil consumption in passenger cars ranges between 0.05% to 0.5% of fuel consumption. While utility vehicles have this range between 0.25% to 0.3%. In case of buses it may go upto 0.5% of fuel utilization.
Normal oil consumption depends on the mileage of engine. Initial 50,000 miles have less oil consumption. It is about one quart for 2000 miles driven. Engines with mileage of more than 50000 miles may consume one quart for 1000 miles.
It all depends upon different factors. These may include driving habits, heavy or easy traffic areas, condition of engine, road, environmental effects and how you maitain your vehicle.
Engine Oil Consumption
Engine oil consumption is not a problem if it is in the normal range. However it is a serious concern if engine consume excessive oil. We shall discuss below the reasons.
Normal Engine Oil Consumption: Why?
There are different factors due to which this happens. One by one we shall consider below.
1. Oil Spill Across the Piston-Ring Pack
Engine oil induces an oil film on the walls of cylinder. Pistons have oil control rings which wipe out lots of oil. However a thin oil film yet remains. As the engine decelerates, a negative pressure produced. It sucks oil in the combustion chamber, burn with fuel and pushed to exhaust.
2. Engine Oil Consumption Due to Evaporation
Engine oil evaporate at high temperatures. Its base oil has volatile ingredients. These become gaseous due to high temperature and evaporate. Its normal range is about 5% to 13%. It thickens the oil due to which viscosity and lubrication performance switched. You can understand the importance of optimal engine temperature.
Engine Overheating Causes: What You Need to Know
3. Low Viscosity Engine Oils Normally Evaporate More
Newer engines particularly require low viscosity engine oils. It is because engine framework contains much narrower clearances. Low viscosity lubricants flow more easily. This serene movement results in a little bit more consumption than high viscosity oil.
Excessive Engine Oil Consumption: Why
Below given factors lead to excessive oil consumption.
1. Leaked Head Gasket
Cylinder head and engine block have large seals among them. It has several passages including passage for oil, coolant circulation and combustion gasses. Vehicle’s fluids will mix together if this gasket blown away. This issue makes it common cause for exessive engine oil consumption.
2. Low Quality Engine Oils
Cheap engine oils have many impurities. These turn into sludge quickly. It increases friction between components. In result, engine overheats and excessive oil consumption occurs. It may leads to complete engine failure.
3. Neglected Oil Leaks Steer Engine Oil Consumption
Engine seals work in high temperature. Overtime these get deteriorated. Sometimes we neglect minor oil marks. It leads engine oil consumption more than normal.
4. Worn Out Piston Rings
Piston rings prevent oil from entering combustion chamber. If there is a combustion fault, fuel accumulates and condensed on the cylinder walls. It wipes out lubrication layer. It produces friction between the cylinder wall and piston. The oil control rings worn out and engine oil enters combustion chamber where it burn with fuel.
5. Incorrect Engine Oil Grade
Wrong engine oil grade matters more than oil brand. It reduces lubrication, in result increases friction which leads to excessive oil consumption.
6. Malfunctioning PCV Valve
The main duty of Positive Crankcase Ventilation (PCV) valve is to let air to escape the crankcase as inside pressure expands too high. A malfunctioning PCV valve may sticks closed. It creates vaccum and high pressure sucks oil past the rings to combustion chamber and burns it with fuel.
7. Aggressive Driving Style: Engine Oil Consumption
Frequent high speed acceleration and deceleration puts extra stress on engine. It raises engine’s operating temperature above optimal. It leads to excessive oil consumption.
8. Low Level of Lubricant
An engine works harder to compensate for low levels of engine oil. It results in high oil pressure to make sure every engine component and passage remain well lubricated. This extra effort overheats the engine.
9. Engine Damage Leads to Engine Oil Consumption
Every engine has a specific lifespan if everything goes well in this period. However, if you want to drive extra miles for long times it needs extra maintenance. Its internal components undergo wear and tear. In particular worn out piston rings are responsible for excessive engine oil consumption.
Total sales volume of automotive oils in Australia in financial year 2020, by type (in megaliters)
