In the maintenance of a heavy vehicle's engine, what type of lubricant does the designation SAE 15W-40 correspond to?

Question

DentroTest · Accepted Answer

SAE lubricating oils with two numbers separated by the letter “W” (for Winter) are multigrade oils. In the SAE 15W-40 specification, the first number (15W) defines the fluidity and pumpability of the lubricant when cold during start-up, while the second (40) indicates its viscosity at the engine's operating temperature, of about 100 °C. It is a multigrade oil because it is formulated with additives to maintain suitable viscosity both cold and hot. It is not an oil exclusively for diesel engines, nor is it sensitive to temperature changes; on the contrary, it is designed to tolerate wide temperature variations. It is not a monograde oil, because those show only one figure (such as SAE 30 or SAE 10W) and have a very restricted temperature range of use.

In the maintenance of a heavy vehicle's engine, what type of lubricant does the designation SAE 15W-40 correspond to?

Want to pass the Permit C and C1 (English) theory test first time?