Zero Double-U Massacree
Evan Zabawski | TLT From the Editor May 2013
Changing oil for a better future.
‘Walk into the store wherever you are and say, “Give me that oil in a 0W.”’
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THE AUTOMOTIVE INDUSTRY has largely switched from SAE xW-30 oils to SAE xW-20 oils. The new SAE xW- 16 oils are also being considered in the interest of increasing fuel economy for new engines. However, might we all benefit from increased fuel economy in our current engines by altering the xW (e.g., 10W, 5W, 0W) classification of the oil we are currently using?
Consider the difference between 10W-30 oil, 5W-30 oil and 0W-30 oil. All SAE 30 oils must have a viscosity in the range of 9.3 cSt to <12.5 cSt at 100 C (close to the bulk oil operating temperature). The 10W designation means the oil also must meet cold weather (or winter—hence the W) specifications for crankability at -25 C and pumpability at -30 C. 5W oil meets nearly identical crankability and pumpability specifications as 10W, only 5 C colder, respectively. 0W oils meet the same specifications as 5W oil, only another 5 C colder, or 10 C colder than 10W oil. Clearly the lower the xW value, the better the oil will perform when really cold.
As recently as 10 years ago, some automotive manufacturers recommended the use of 10W-30 year-round and suggested 5W-30 be used if the ambient temperature went below freezing. The recommendation of 10W-30 has dropped in favor of 5W-30 for most automotive applications, but it is slow to shift from 5W-30 to 0W-30, even though 0W-30 has been commercially available for decades. This could be due to the stigma of 0W oils being winter oils. No doubt branding oil “polar” or “arctic” doesn’t help convince drivers that it is the best year-round oil, but they might be convinced if they knew how these oils behaved when they are hotter than bulk operating temperature.
The piston-ring interface sits around 160 C (300 F), and comparing 10W-30, 5W-30 and 0W-30 gives the surprising revelation that 0W-30 oil is about 10% thicker than either of the other two at that temperature. This is due to the viscosity index (the variation of viscosity with temperature), which should make sense. For an oil to be relatively thinner than another at cold temperatures, but equal at a warmer temperature, it must have less variance in viscosity with temperature. Therefore as the oil’s temperature increases, it will not thin out as much as the other and provides a superior film of lubrication that is able to reduce friction and wear.
Better viscosity indices amount to increased fuel economy, but how much? Some suppliers may promise up to 2%, but my personal experience is far greater. When I switched my first vehicle over from 5W-30 to 0W-30, I gained nearly 10% (data collected using 10 oil drains, each fully synthetic oil, in a 4-cylinder gas engine). The second vehicle I switched was from 5W-20 to 0W-20, where I gained 13% (Note: I did not alter the actual grade of the oil in order to honor warranty requirements).
Needless to say, I am a convert just sitting here on the bench that says, “Group 0W.” And the only reason I’m telling you this now is because you might know somebody in a similar situation, or you may be in a similar situation, and if you’re in a situation like that, there’s only one thing you can do and that’s walk into the store wherever you are and say, “Give me that oil in a 0W.”
So the next time you are getting your oil changed, just ask for 0W oil. You know if one person, just one person does it, they may think they misheard him and they won’t sell it to him. And if two people, two people do it, in harmony, they may think they’re both mistaken and they won’t sell to either of them. And if three people do it, three, can you imagine, three people walking in asking for 0W oil? They may think it’s an organization. And can you imagine 50 people a day? I said 50 people a day walking in asking for 0W oil? And friends, they may think it’s a movement.
With respect and apologies to Arlo Guthrie who has been singing his influential song for more than 45 years.
Evan Zabawski, CLS, is a reliability specialist in Calgary, Alberta, Canada. You can reach him at evan.zabawski@gmail.com.