What is 10W40 oil used for?

10W40 engine oil is typically added to vehicles during summer months or when the temperature is high. The '10' indicates a higher viscosity index, meaning this oil can withstand hot temperatures before it starts to thin.

Does it matter if I use 10W40 instead of 5W30?

Yes, your choice of engine oil will affect overall performance. 5W30 oil has a lower viscosity index, so it won't be as suitable for warmer temperatures and climates; in this case, you would choose 10W40 engine oil instead.

When should I use 10W40 oil?

You should opt for 10W40 engine oil if you plan on driving in warm temperatures. This oil is thicker and therefore maintains its viscosity for longer, enabling it to keep lubricating the engine's parts.