Q: How Does the Oil Lubrication Process Work in the Engine?

The lubrication system in an automotive engine is vital to having a long-lasting engine with normal operating temperatures and metal wear. The lubrication will flow between all the rotating metal components to reduce wear and heat-related damage from friction between the two parts.

The system starts with an oil pan or sump at the bottom of the engine that will store the oil for an engine to utilize as a lubrication product storage. Once started, the engine will turn the oil pump. The pump can be gear, chain, or shaft driven. The pump will start sucking oil from the oil pan. The oil is sucked into the oil pump inlet tube and the pump will pump out a high volume of oil supply to the engine through passages and a filter. The oil pump is a demand style pump and will supply more oil as the engine RPM increases. The oil is then pushed into the oil filter to be filtered before going to the various engine components to keep them lubricated.

The oil filter can be one of two different types: metal canister with a paper or metal screen inside it or a paper or metal filter designed to go into a housing on the engine with a sealed top. Both filters are designed to filter out impurities in the oil before the oil is sent to the rest of the motor. The only part that gets non-filtered oil is the oil pump. An oil filter needs to be changed at intervals recommended by the manufacturer to keep the oil as clean as possible. After leaving the oil filter, the oil will be clean enough to be distributed to the main engine components and the first component to get the oil is the engine crankshaft main bearings. Once the oil is pumped into the main bearings, it goes into the rod bearings and up through the rods into the piston wrist pins and piston. The oil will travel up through passages in the engine block to the engine head and valve train to be distributed to the camshafts and the valve train.

Depending on the type of engine you have, if it is an overhead cam or double overhead cam engine (OHC, DOHC), then it will have the camshafts mounted on top of the cylinder heads. These types of engines will have camshaft followers that will follow the cam and push down on the valve and valve spring to open the valves. If the engine is an overhead valve engine (OHV) with a single cam mounted inside the engine block, there will be lifters that follow the cam and then push rods that will go up to the rockers that will have a pivot point that opens and closes the valves for you. Both of these engines may have a timing chain and gears. All of these components need to have constant and complete lubrication while they’re rotating.

When an engine is running and the lubrication system is lubricating the components, there is a certain amount of metal to metal contact. Dirt and debris that gets into the engine will get suspended in the oil. After the oil has lubricated the upper part of the engine, the oil will drain back into the oil pan to be pulled into the engine again through the oil pump and then into the filter again to filter out all the dirt and debris that was suspended in the oil. This process will continue as long as the engine is running. The oil and filter should be changed to get out excess dirt, metal, and debris the engine oil and filter accumulates between services.