oil

The second number after the “W” indicates the oil’s viscosity measured at 212 degrees Fahrenheit (100 degrees Celsius). This number represents the oil’s resistance to thinning at high temperatures. For example, 10W-30 oil will thin out at higher temperatures faster than 10W-40 will.
What are oil grades | Lubricants – Total Lubricants

Motor oil provides lubrication to the many moving parts of an engine, which helps to avoid damage and keep your engine running smoothly. Each time your engine runs, by-products from combustion are collected in your engine oil.Jun 19, 2020
Everything You Need to Know About Motor Oil