With almost 30 years’ experience in the oil and lubricants industry, Morris Lubricants’ Automotive Product Manager, Adrian Hill, is perfectly placed to provide his expert insight and analysis.
Q. I have previously used 15W-40 and 10W- 40 in my vehicles. Now when I buy oil, I see some that say 5W-30 and even 0W-20. Why is there such a difference between the grades now and what I used to purchase, and what do they actually do differently?
We have seen, over recent years, the introduction of after-treatment devices such as diesel particulate filters, catalysts and, more recently, Adblue. These devices clean up exhaust gases either by removing particulates, such as soot, or by converting carbon dioxide and nitrogen oxides to harmless alternatives (carbon dioxide, nitrogen and water).
The irony here is that carbon dioxide is also seen as a harmful exhaust gas and is better known as a greenhouse gas. There isn’t any technology available to remove carbon dioxide by converting it, so engine manufacturers have to try and
reduce the quantity of carbon dioxide an engine produces. To do this they are continually striving to produce engines which are more fuel efficient – burning less fuel to go the same distance means less carbon dioxide produced.
This is where engine oil can help. The thicker the oil, the more friction there is and the more energy is expended to move the oil around all the moving parts. Moving to thinner 5W-30s, 0W-30s, 0W-20s and even 0W- 16s reduces internal friction, contributing to the engine’s improved fuel efficiency and helping to reduce the levels of carbon dioxide produced.