The biggest noticeable difference I've seen in using the BMW 0W-40 is how long the engine takes to warm up. It seems to now take TWICE as long to warm up compared to the Castrol TWS 10-60. Both oils seem to crank about the same down to -20C and I drive off immediately. But, I thought a fast warm-up was the best thing for an engine. Aside from taking longer to warm-up the passenger compartment, is this increased warm-up time a bad thing for engine wear? Anyone experience this with a OW?