Question #efca2

1 Answer
Jun 23, 2017

see below


an automotive oil must have little change in viscosity with the change of temperature, because it must be usefull (lubricate) when the engine is cold (before you start) and when the engine is hot (it is cooled with water or special fluids, but it works around 100°C). An multigrade oil can keep the viscosity quite costant while a monograde oil not. Chimically they are mineral oils (hydrocarbons with high molecular weigh) that change its geometrical form stretchhing and rolling up at the different temperatures