What is the primary method to heat ice-cold oil type #6 to operating temperature?

Using a heated tanker is indeed the primary method for heating ice-cold oil type #6 to its operating temperature. This option is effective because heated tankers are specifically designed to maintain and control the temperature of the oil as it transfers from one location to another. These tankers are equipped with heating systems that ensure the oil is warmed adequately for effective use in stationary engineering applications.

Alternatives like letting it sit in sunlight, mixing it with hot water, or storing it in a warm location may provide some heat but are generally inefficient and unreliable. Sunlight may not deliver consistent or sufficient warmth, especially on cold days. Mixing oil with hot water can cause emulsification or unwanted chemical reactions, which may alter the properties of the oil. Storing it in a warm location can help, but it may take an extended amount of time and is not as effective as direct heating mechanisms found in heated tankers. So, using a heated tanker remains the preferred and most efficient method to ensure that oil type #6 reaches the necessary operating temperature without compromising its quality or effectiveness.