I've been using 85W-140 in all my vehicles, cars and trucks, for many years. The "W" stands for "winter", and the flow rate is measured at zero degrees, Farinheit, I believe. It just flows a little better and lubricates well at very low temps. 90 weight and similar straight viscosity oils get as gummy as molasses as the temperature drops, adding a lot of drag and not doing a very good job oif lubricating bearings.
Jerry


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