Couple of facts that people seem to have a hard time getting across lately, pertaining to warm-up, oil temperatures, and why OEMs are switching to lighter viscosities, and the Japanese penchant for higher VIs.
Here's a map of the energy input into heating the oil in the first minutes after start-up, taken from
https://edupediapublications.org/journals/index.php/ijr/article/download/925/875
In that 1.7L 4 cylinder engine, at cold start, the work that the rotating assembly is doing to the oil is 4KW, there's 4KW of heat, just due to viscous friction heating the oil (and consequently the block and coolant) in the first minutes...
That's where the lower KV40/Higher VI lubes are saving the manufacturers money in CAFE credits...and saving the end user fuel as well, obviously.
In a country where the majority of trips are less than 10 minutes, then it's clearly a winner.
And contrary to popular opinion, if you have a look at the 9 minute and onwards, the contribution to oil heat rejection is about evenly split between internally generated viscous friction, and that transferred to it through combustion.
Here's a map of the energy input into heating the oil in the first minutes after start-up, taken from
https://edupediapublications.org/journals/index.php/ijr/article/download/925/875
In that 1.7L 4 cylinder engine, at cold start, the work that the rotating assembly is doing to the oil is 4KW, there's 4KW of heat, just due to viscous friction heating the oil (and consequently the block and coolant) in the first minutes...
That's where the lower KV40/Higher VI lubes are saving the manufacturers money in CAFE credits...and saving the end user fuel as well, obviously.
In a country where the majority of trips are less than 10 minutes, then it's clearly a winner.
And contrary to popular opinion, if you have a look at the 9 minute and onwards, the contribution to oil heat rejection is about evenly split between internally generated viscous friction, and that transferred to it through combustion.