Heat transfer oil with high auto ignition temperature

A process to prepare a heat transfer oil, comprising:

• a. dewaxing a substantially paraffinic wax feed by hydroisomerization dewaxing using a shape selective intermediate pore size molecular sieve under hydroisomerization conditions including a hydrogen to feed ratio from about 712.4 to about 3562 liter H2/liter oil (about 4 to about 20 MSCF/bbl), whereby a lubricating base oil is produced,
• b. selecting one or more fractions of the lubricating base oil having:
• i. a pour point less than −9° C.,
• ii. greater than 10 weight percent and less than 70 weight percent total molecules with cycloparaffinic functionality, and
• iii. a ratio of weight percent molecules with monocycloparaffinic functionality to weight percent molecules with multicycloparaffinic functionality greater than 15;
• and
• c. blending the one or more fractions of the lubricating base oil with less than 0.2 wt % antifoam agent to prepare the heat transfer oil of an ISO viscosity grade selected from the group of ISO 10, ISO 15, ISO 22, ISO 46, ISO 68, ISO 100, ISO 150, and ISO 220.

A method to use a heat transfer oil, comprising:

• a. selecting a heat transfer oil having an auto ignition temperature greater than 329° C. (625° F.) and a viscosity index greater than 28×Ln(Kinematic Viscosity at 100° C., in cSt)+80;
• wherein the heat transfer oil comprises a base oil, made from a waxy feed, with the base oil having:
• i. greater than 10 weight percent and less than 70 weight percent total molecules with cycloparaffinic functionality;
• b. providing the heat transfer oil to a mechanical system;
• and
• c. transferring heat in the mechanical system from a heat source to a heat sink.