Lubrication System
How oil protects bearings and removes heat, and why oil pressure and quality decide engine life.
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What you will learn
- Trace oil from the sump to the bearings
- Explain oil pressure and flow
- Recognise the symptoms of oil starvation
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The lubrication system does three jobs: it separates moving surfaces with an oil film, it carries heat away from bearings and pistons, and it transports wear particles to the filter. A running engine depends on a thin, pressurised film delivered continuously.
The pump draws oil from the sump through a pick-up strainer, pushes it through the filter and into galleries that feed the crankshaft and camshaft bearings, then it drains back to the sump. Pressure and flow are different things: a worn engine can show low pressure and still circulate oil, while a blocked pick-up can starve the whole engine.
| Component | Job | Failure symptom |
|---|---|---|
| Oil pump | Pressurises the oil | Low pressure, especially when hot |
| Pick-up strainer | Filters large debris | Pressure drop, starvation on corners |
| Oil filter | Traps fine particles | Bypass opens, dirty oil recirculates |
| Pressure switch | Warns of low pressure | Light on at idle or when hot |
| PCV system | Controls crankcase pressure | Oil consumption, seal leaks |
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If the oil pressure warning light comes on while driving, stop the engine as soon as it is safe. Continued running with no pressure destroys bearings in seconds.
Key points
- Correct oil specification and level protect the whole engine.
- Low pressure when hot points to wear or a weak pump.
- A restricted pick-up starves bearings even with good oil.
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Key points
- Oil lubricates, cools and cleans
- Pressure protects bearings; flow removes heat
- The oil light means stop, not “top up later”
Sources & references
- Vehicle manufacturer lubrication chapter
- Oil specification charts (choose by engine code, not by brand)
All values shown are training examples. Real thresholds depend on the manufacturer, engine, temperature and system — always confirm with the vehicle service documentation.
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