W is 2nd gear start and lower rpm shift points to reduce torque in rain/mud/snow.

Some use W all the time; most of us use S. Either is acceptable; is personal preferance based on driving style.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)