Truth Man solves the puzzle: The greater the viscosity of the engine oil, the quieter it is and the more fuel it consumes?

【Car owner’s home car knowledge】Recently, when Truth Man was on the forum, he discovered that a certain issue had been discussed by netizens for a long time: the higher the viscosity of the engine oil, the more obvious the increase in fuel consumption, but the lower the engine noise. Although theoretically speaking, using oil with high viscosity in the engine will increase fuel consumption and change the noise, but is there a significant difference in the actual situation as netizens said? It just so happened that the truth man had some oils of a certain brand with different viscosities on hand, so he took his car key while his colleague was away, so that he could test it in practice. Without further ado, let’s get started right away.

● Netizens’ personal experience: After switching to high-viscosity engine oil, the car’s fuel consumption increased and the noise changed.

In a forum for a certain brand and car model, a netizen recounted his experience of "increased fuel consumption" after switching to high-viscosity engine oil:

In addition to fuel consumption, engine noise changes are also a topic of discussion among netizens.

● What will Truth Man test this time?

How much impact does engine oil viscosity have on vehicle fuel consumption and engine noise? In order to see this gap clearly, Truth Man found three engine oils of different viscosities and a test car to do a simple test.

● This test method and instruments and tools

Test object: Truth Man has three common viscosity motor oils of the same brand on hand, namely 5W-30, 5W-40, and 5W-50. The car that the Truth Man came to was a Dongfeng Citroen New Sega, which had traveled more than 10,000 kilometers. The engine oil used in it had a viscosity of 5W-30, which was suitable for use as a test car.

Test instrument: digital noise meter

Test method: We added the engine oil viscosity in order from low to high (5W-30→5W-40→5W-50) into the test vehicle respectively, and replaced the oil filter each time to reduce the residual amount of old oil as much as possible.

After the car was warmed up, we drove the car to a gas station (actually the gas station is right next to the oil change location), filled the tank (to the point where the oil level was visible), then ran a lap along the predetermined route, returned to the gas station and filled the tank again, and calculated the average fuel consumption value of the test based on the fuel volume and subtotal mileage. The noise test of the three types of engine oil was conducted on fixed sections of the road.