1. EO M232.04
Engine Oil in a Four Stroke Engine
1x30m w/FSgt Aikens

2. Importance
We’ve been talking about engines for a couple of weeks, knowing what you know now, why would an engine need oil?
Oil is required for the engine to function, and it also makes the engine more efficient and increases performance.

3. Oil There are 4 reasons we have oil in the engine: Lubrication Sealing
Cooling
Flushing

4. Lubrication
Oil creates a smooth surface between engine parts that rub together (ex: piston and cylinder). This reduces wear and tear and heat caused by friction.
This next part is taken directly from the book:
But I doubt that you’ll need to know this for level two.

5. Sealing
Engine oil fills small cracks and seams between engine parts to help contain gasses from escaping.
Higher viscosity oil will seal better, but won’t lubricate well.
Lower viscosity oil will lubricate well, but won’t seal.
To add to that; oil viscosity changes with temperature, lowering as
the oil heats up.

6. Confirmation What are the four reasons for having oil in the engine?
Lubricating, Sealing, Cooling, Flushing
How does oil lubricate the engine?
It provides a barrier between moving pieces
What does ‘sealing’ mean?
The oil fills gaps and seams to lock gasses in.
What are the conflicting demands that oil has to meet?
It needs to be low viscosity to lubricate, but higher to seal.

7. Cooling
Some parts of the engine get hotter than the others. Particularly around the cylinders.
Oil moves around in the engine and can carry away heat and circulate back to cool down engine hot spots.
It is important that oil doesn’t change viscosity when heated so that it still fulfills its other functions.

8. Flushing
As the oil circulates through the engine, it picks up dirt, debris, and bits of metal, all harmful to the engine.
The oil then passes through a filter that removes large debris, but smaller debris stays trapped in the oil.
This is why it is important to change your oil and oil filter.
(Also some oil leaks out and some gets burned inadvertently over time)

9. Confirmation How does oil cool the engine?
By circulating through and removing heat from hot spots
What is the final function of oil?
Flushing
And what is that?
Catching and removing harmful debris from the engine
What part needs to be regularly changed along with the oil?
The oil filter

10. End of Class
That was EO M232.04, Functions of oil in the engine.