Military and commercial jet aircraft engines operate hotter than in the past to increase fuel efficiency. Also, advanced structural engine materials permit hotter burning, more efficient engines. These trends are expected to continue. Many current gas turbine engines experience oil system coking and other problems related to the limited thermal and oxidative stability of the conventional, ester-based gas turbine engine oils. This is because most engines operate on gas turbine oils limited to 150°C. The best current oils have a maximum operating temperature of about 200°C. We initiated a program to develop a new class of ester-based lubricants to meet current and future high-temperature requirements. The target temperature range of this new oil is −40°C to 232°C. Target requirements were established and communicated to industry. This paper presents those requirements and initial results on the most promising candidates.