Volkswagen Golf 2003 1.4 petrol service and maintenance
Engine oil
Engine oil capacity: 3.2 litres (3.4 quarts)
Recommended oil type (Oil Viscosity Classification SAE) is 5W-30
Timing belt
Manufacturers recommended timing belt replacement interval for Volkswagen Golf 1.4 petrol is 90,000 km.
Based on practical experience, recommended Volkswagen Golf 2003 1.4 16V timing belt change interval is 40,000 km when belt should be replaced, or at least periodically check the belt's condition after this mileage and replace it at the first sign of damage.
Running your car in aggressive environments (e.g. salt, sand, etc.) causes timing belt to degrade faster and reduces its lifespan; under such conditions, the belt may need to be replaced sooner.

Volkswagen Golf 2003 1.4 16V 2003 - 2006 Volkswagen Golf 2003 technical data
Volkswagen Golf 2003 owner reviews
Always consult your vehicle manufacturer's service manual for service intervals and specifications!