Originally Posted By: dailydriver
Originally Posted By: CATERHAM
M1 0W-40's higher VI means it's lighter on start-up than both Castrol 0W-40 and even GC 0W-30. How much lighter? It's still 10% lighter at 60F and progressively more so at lower temp's and this is despite M1 having a significantly higher HTHSV.
Now, can the same thing be claimed for the Red Line 0W-40 over the sacred 'holy grail' M1 0W-40??
In other words, does RL's higher VI make it thinner than the M1
at ALL temps, DESPITE it's ~.2 higher HTHSV, or is the VI difference not great enough to make up for that HTHSV difference?
M1 0W-40 is the "bench mark" 0W-40 because it's an OEM oil with spec's that are very hard to beat, not to mention it's available everywhere and reasonably priced.
The 'holy grail' is a VI as high as possible and the 197 VI of RL 0W-40 is the highest of any 30wt or heavier oil in NA but due to it's higher 4.0cP HTHSV I think it will be heavier than M1 0W-40 at all temp's.