Lubrication and Vehicle Fluids

What each fluid does and why the right spec matters.

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What you will learn

Identify the main fluids
Explain oil specification
Recognise fluid-related faults

Vehicles depend on several fluids: engine oil lubricates and cools, coolant controls temperature, brake fluid transmits pressure, transmission fluid does both lubrication and hydraulic work, and screen wash is a safety item. Each has a specification chosen by the manufacturer.

Using the wrong fluid — the wrong oil viscosity, the wrong coolant type or the wrong transmission fluid — can cause premature wear or component failure. Checking levels and condition is a routine but critical part of every service.

Fluid	Job	Spec matters?
Engine oil	Lubricate, cool, clean	Yes — viscosity and standard
Coolant	Heat transfer, corrosion	Yes — OAT/HOAT type
Brake fluid	Transmit hydraulic force	Yes — DOT type
Transmission fluid	Lubricate and actuate	Yes — very specific

Key points

Every fluid has a job and a specification.
Wrong fluid causes wear long before obvious symptoms.
Check level and condition at every service.

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Key points

Each fluid has a specific job and spec
Wrong fluid causes premature wear
Levels and condition are routine checks

All values shown are training examples. Real thresholds depend on the manufacturer, engine, temperature and system — always confirm with the vehicle service documentation.