Heavy crudes (high wax content, high API viscosity, high density) cannot be refined efficiently by refineries geared to refine light crudes and vice versa.

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The majority new oil being developed are heavy, sour crude oils which have a high sulfur content, high viscosity, and high density.

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Viscosity is all about texture, or mouthfeel in wine, high viscosity adds weight to the experience.

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But heart attacks can strike even those without traditional risk factors such as high cholesterol levels, suggesting that high viscosity is a possible cause.

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