5W-20, 5W-30 or 10W-40? A Quick Guide to Engine Oil Viscosity

❓ What do oil grades like 5W-30 mean?

• “W” stands for Winter (cold-start performance)

• The first number shows how well the oil flows in cold temperatures

• The second number shows oil thickness at normal engine temperature

Lower numbers = better cold start
Higher numbers = stronger high-temperature protection

❓ What is 5W-20 used for?

• Designed for modern engines

• Improves fuel efficiency

• Very thin oil for tight engine tolerances

Best for: New petrol engines, hybrids
Note: Only use if specified by the manufacturer

❓ Why is 5W-30 so popular?

• Balanced performance in most conditions

• Suitable for both petrol and diesel engines

Best for: Daily driving, most modern vehicles
Most commonly recommended grade

❓ When should I use 5W-40?

• Thicker protection at high temperatures

• Handles turbocharged and high-load engines better

Best for: Turbo engines, performance cars, high-mileage vehicles

❓ Is 10W-30 different from 5W-30?

• Thicker during cold starts

• Similar protection once the engine is warm

Best for: Older engines, warmer climates

❓ Who should use 10W-40?

• Thicker oil film helps reduce oil consumption

• Ideal for engines with wear

Best for: High-mileage and older vehicles

✅ Final Tip

Always follow your vehicle manufacturer’s recommended viscosity and specifications. MANNOL engine oils are available in multiple grades to match OEM requirements and driving conditions.