Seen as 10W-40 Mid SAPS oils have fuel-saving capabilities, switching to them from a 15W-40 CI-4 is a popular move. However, some see a slight increase in oil consumption. How should you interpret that? Read on to find out more.
Before we dive into the particularities of each oil type, let’s sum up why engine oil gets consumed (used up) in the first place. There are two main causes:
How do these play a role when you compare 10W-40 Mid SAPS oils and the 15W-40 CI-4?
Inside a running engine, it is literally burning hot. And so, any engine oil slowly evaporates.
In our lab, we continually test the oil consumption from evaporation. Of course, 10W-40 Mid SAPS oils meet and exceed all requirements, or we wouldn’t distribute them. What’s more, we’ve tested the OEM SPECIFIC 10W40 ULTRA MS (a Mid SAPS) against the NEW ENERGY 15W40, and the Mid SAPS oil actually shows a lower consumption from evaporation.
In short, evaporation most likely does not cause higher oil consumption.
The cause for their supposed higher oil consumption, then, is lower viscosity.
To meet the latest ‘Euro’ emission standards, car manufacturers produce engines with less friction between their moving parts.
These engines demand oils with a lower viscosity, such as Mid SAPS oils. Because they are thinner, they enter the combustion chamber quicker than e.g. a 15W-40 CI-4 and are therefore burned (consumed) faster.
As we’ve seen, a Mid SAPS’ surplus in oil consumption is due to their lower viscosity.
But it is negligible when you consider the fuel they save: up to 1% under normal driving conditions. Road tests, performed by one of our major clients, have even shown up to 4% fuel savings after switching from a 15W-40 to a 5W-30 Heavy Duty lubricant.
The conclusion? What is lost in oil is more than won in fuel savings. Switching to a 10W-40 Mid SAPS, therefore, is a smart idea, after all.
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