Can you use 10-40w motor oil in your petrol lawn mower?

No, you should not use 10-40w motor oil in your petrol lawn mower. Petrol lawn mowers typically require SAE 30, SAE 10W-30, or 5W-30 oil, depending on the manufacturer's recommendations.

10-40w motor oil is too thick for most petrol lawn mowers and can cause engine damage. The higher viscosity of 10-40w oil can impede oil flow and lubrication, leading to increased wear and tear on engine components. Additionally, the thicker oil may make it harder for the engine to start in cold weather.

Always refer to your lawn mower's owner's manual for the recommended oil type and viscosity to ensure optimal performance and longevity.