Quote:
Originally Posted by timurrrr
As far as I understand, 0w-40 will still have lower viscosity at startup than 5w-30? I wonder why most people do 5w-30 and 0w-40 is rarely mentioned.
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No, typically 5W-30 falls in between the viscosity levels of 0W-20 and 0W-40 for startup and operating temperatures. Oil brands have different viscosity ratings as well, so it really depends. For some brands, like AMSOIL, even 10W-30 has a lower viscosity than 0W-40. But there is also the additional factor of how "cold" the cold start is. With a better viscosity index, the 0W-40 will have a lower viscosity at extremely cold temperatures well below 32F (at least in the case of AMSOIL). It's a very complicated subject honestly, which is why you never stop hearing about it.