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The Journey of Oil In My Engine

Published June 7, 2018 in Uncategorized - 0 Comments

Most of us know that it is important that our internal combustion engines have oil and the level should be checked regularly.  We know that we add oil and that it drains to the bottom of the pan.  Unless you’re a professional mechanic or avid car enthusiast may not know just the many roles oil in our vehicles play to keep the vehicle running.  The main question most of ask is how often should I change the oil and what oil should I use.  To answer these questions, I will use this blog to take you on the journey that your oil travels inside your engine.

To guide you on this journey I have included a figure taking you inside the Internal Combustion Engine and see how moves through the engine in this video. How Engine Oil Lubricates an Engine

All the oil drains to the oil pan (sump) when the engine is not operating.  On starting the engine oil is sucked up through the sump strainer and tube shown in the Figure.  Note that the strainer is submerged into the oil pan to a depth of 4 inches.  The strainer prevents large pieces of debris (larger than 1/32 nd inches) from entering the oil pump.

The oil pump is a series of gears that take the oil from low pressure to high pressure through a chamber with a spring loaded valve that maintains pressure between 1- 60 psi.  Any pressure higher than this vents the oil back to the sump because high pressure can damage the main bearings.

The oil is then pumped through the oil filter, which also has a bypass valve to insure oil get pumped into the engine if the filter gets clogged.  This is because oil need to be under pressure to lubricate the rotating parts of the engine.

Under pressure the oil is forced into the space between the bearings and contacting the crankshaft journals.  The bearings are metal sleeves encircling the rotating components of the engine.  The main bearings on the crankshaft and the connecting rods bearings on the crank throw. A very thin film of oil usually one thousandth of an inch is held between the bearings and the moving surfaces of the crankshaft. This oil layer keeps the moving metal parts from touching.

Some of the oil is forced outside the bearings and drips back to the sump. If the bearings are wearing, this gap will result in a drop in pressure in the upper part of the engine.  A flickering oil light or slight tapping in the rocker arm area of indicates that there is not enough pressure reaching the top of the engine.

Most of the oil lubricates the crankshaft and the remainder lubricates the camshaft and rocker arms. If your vehicle has pushrods (most older cars) vs overhead camshaft the oil is forced under pressure into the valve lifters. The lifters also push oil through the hollow push rods lubricating the rocker arms.  If you vehicle is an overhead cam design, the oil flows onto cam and drips onto the contact point between the cam and the valve stems.

In the overhead cam engine design the oil then flows back down channels in the head and motor block back to the sump. In connecting rod design as shown in the figure, oil is sprayed into the cylinder to lubricate the piston ring contact are of the cylinder. Special rings on the bottom of the ring set wipe the excess oil from the cylinder wall to drain back to the sump.

Now that we know the journey oil takes in your engine, in the next blog I will delve into choosing the proper oil and easy ways to monitor the health of your oil.

Knowing the importance of oil in keeping your vehicle running , you will amazed to see that we produce an engine oil supplement that contains space age nano-technology that penetrates and protects the metal surfaces of an engine even when there is no oil. We never recommend running any engine without oil but we have run a used V8 engine with 281K miles on it without oil. You can see the video at



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