Diesel engine oil typically possesses a higher level of viscosity, which means it pumps at a much lower temperature and takes more heat to start flowing cleanly.

Demands on heavy-duty diesel engine oils ... to a lower viscosity engine oil was concern around wear protection and engine durability,” says Len Badal, global brand manager at Chevron.

In the past, there have been similar shifts in preferred engine oil viscosity grades. An example is the transition in heavy duty diesel engine oils in the 1980s from monograde viscosity SAE 30 and ...