53Types and Properties of Lubricating Oils
Type II turbo oils were commercialized in the early 1960s to meet demands from the
U.S. Navy for improved performance, which created MIL-L (PRF)-23699. The major-
ity of aero-derivatives in power generation today deploy these type II, MIL-L (PRF)-
23699, polyol ester base stock, synthetic turbo oils. These type II oils offer signicant
performance advantages over the earlier type I diester-based synthetic turbo oils.
Enhanced type II turbo oils were commercialized in the early 1980s to meet the
demands from the U.S. Navy for better high-temperature stability. This led to the
creation of the new specication MIL-L (PRF)-23699 HTS. In 1993, Mobil jet oil
291 was commercialized as the rst fourth-generation ...