This it completely unscientific, and is just an observation.
I took a bottle of Toyota 0W20 SN from my collection and shook the bottle. Its contents sounded extremely watery compared to any oil bottle I have ever shaken. The recent VOA showing a 40C viscosity of about 37cST proves that it is the thinnest 0W20 at that temperature.
As a comparison, I have a new bottle of Castrol Edge w/Titanium (Gold Bottle) 5W20, SN. The 40C viscosity of this oil is 49.9, which is about average (or slightly thicker) than the average 5W20 at 40C. In comparison, when this bottle of oil was shaken, it did not nearly as watery. After looking at the numbers, the Toyota 0W20 is 20% thinner at 40C.
Clearly this is not scientific and is just an observation on my part. However, it leads me to believe that the Toyota 0W20 must have a significant advantage in short trip conditions because the oil should have a noticeable reduction in pumping losses compared to many 5W20s, or even some 0W20s. There are some people on a different forum who have observed a 1-2mpg loss from switching to Mobil 1 0W20 from Toyota 0W20 (about 3% in their case), which is quite believable if the car was a short tripper where oil temperatures stayed well below 212F.
I took a bottle of Toyota 0W20 SN from my collection and shook the bottle. Its contents sounded extremely watery compared to any oil bottle I have ever shaken. The recent VOA showing a 40C viscosity of about 37cST proves that it is the thinnest 0W20 at that temperature.
As a comparison, I have a new bottle of Castrol Edge w/Titanium (Gold Bottle) 5W20, SN. The 40C viscosity of this oil is 49.9, which is about average (or slightly thicker) than the average 5W20 at 40C. In comparison, when this bottle of oil was shaken, it did not nearly as watery. After looking at the numbers, the Toyota 0W20 is 20% thinner at 40C.
Clearly this is not scientific and is just an observation on my part. However, it leads me to believe that the Toyota 0W20 must have a significant advantage in short trip conditions because the oil should have a noticeable reduction in pumping losses compared to many 5W20s, or even some 0W20s. There are some people on a different forum who have observed a 1-2mpg loss from switching to Mobil 1 0W20 from Toyota 0W20 (about 3% in their case), which is quite believable if the car was a short tripper where oil temperatures stayed well below 212F.