Originally Posted By: Gokhan
The question here was whether lower MRV/CCS necessarily means lighter oil when the engine is cold.
The answer, as implied by CATERHAM, is no. For a given y of *W-y SAE viscosity grade, how light an oil when it's cold is given by the viscosity index, not MRV/CCS. Higher the viscosity index, lighter the oil will be when it's cold.
The implication that VI trumps cold pumping for cold pumping is false...the implication that VI in any reasonably chosen oil has marked advantages similarly false.
API have chosen pumpability precisely because that is what they are trying to simulate.
I can get a 5W-30 with a 192VI down here, which some on this board would tell you has better extreme cold performance than a 0W-30...by extreme, temperatures that aren't 40C(ish)
The question here was whether lower MRV/CCS necessarily means lighter oil when the engine is cold.
The answer, as implied by CATERHAM, is no. For a given y of *W-y SAE viscosity grade, how light an oil when it's cold is given by the viscosity index, not MRV/CCS. Higher the viscosity index, lighter the oil will be when it's cold.
The implication that VI trumps cold pumping for cold pumping is false...the implication that VI in any reasonably chosen oil has marked advantages similarly false.
API have chosen pumpability precisely because that is what they are trying to simulate.
I can get a 5W-30 with a 192VI down here, which some on this board would tell you has better extreme cold performance than a 0W-30...by extreme, temperatures that aren't 40C(ish)