10W-40 Mid SAPS lubricants are developed to save fuel. But it seems the oil consumption is higher than that of a 15W-40 CI-4 oil. What’s the story here?
Let’s first look at why oil ‘gets consumed’. At high temperatures, like inside running engines, oil slowly evaporates over time. Evaporation is the first cause of oil consumption.
We continuously measure this oil consumption in our laboratory as part of our ongoing quality tests. These tests show that the oil consumption of a 10W-40 Mid SAPS amply meets the requirements. Moreover, we tested the WOLF OFFICIALTECH 10W40 ULTRA MS (a Mid SAPS), and the oil consumption from evaporation was actually lower when compared to the WOLF VITALTECH 15W40.
But there is another cause for oil consumption: viscosity. Car manufacturers must meet the latest ‘Euro’ emission standards. To that end, they create engines with less friction, meaning less fuel consumption and lower emissions.
Lubricant manufacturers, in their turn, have to produce lubricants with a lower viscosity (meaning thinner) for these engines. These oils enter the combustion chamber much quicker. As a consequence, more oil is burnt. Oil consumption due to lower viscosity is probably higher when using 10W-40 Mid SAPS lubricants.
Nevertheless, the slightly higher oil consumption of a 10W-40 Mid SAPS is negligible when considering the fuel it saves. Under normal driving conditions, it can save up to 1% in fuel. Road tests executed by one of our major clients have even shown up to 4% saving in fuel after having switched from a 15W-40 to a 5W-30 Heavy Duty oil.
The bottom line: 10W-40 Mid SAPS lubricants may have a slightly higher oil consumption, but the fuel saving more than makes up for it.
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