may i ask Nick , why you do not speak of 10W60 ?
we use that in all our BMW engines....
i can imagine we have more profit of high temp protection instead of by - 30 °C ?
If you look at a good number of used oil analysis results for 10W/60 oils you will find that most of them shear to a xW/50 within 2,0000 to 3,000 miles and they have these days gone out of fashion as an OE recommendation.
I believe that BMW and Alfa Romeo do specify them for some of their older engines but I have not seen them recently specified for newer cars.
Due to the excellent results obtained from the latest 0W/20 oils they have virtually taken over for new cars due to their fuel saving properties.
Therefore 10W/60 is more of a racing oil or used in problem engines that tend to put a lot of heat into their oil but results advise short duration in the life of the oils at high temperatures.
